OCLC: 


SKETCHING  METHODS 


By  W.  C.  SWEENEY 

Captain,  Twenty-first  United  States  Infantry 


EDITED  AT 

THE  ARMY  WAR  COLLEGE 


OCTOBER,  1917 


' 


. 

And  printed  under  the  license  of  t!.e 
right 

! 


grantee  of  the  copyright 

*-' 


WASHINGTON 
GOVERNMENT  PRINTING  OFFICE 

1917 


WAR  DEPARTMENT, 

Document  No.  679, 
Office  of  The  Adjutant  General. 


WAR  DEPARTMENT, 
WASHINGTON,  October  16,  1917. 

The  following  pamphlet,  "  Sketching  Methods,"   Sweeney,  is 
published  for  the  information  of  all  concerned. 

[461,  A.  G.  O.] 
BY  OBDEB  OF  THE  SECRETARY  OF  WAB  : 

TASKER  H.  BLISS, 

General,  Chief  of  Staff. 
OFFICIAL  : 

H.  P.  MCCAIN, 

The  Adjutant  General. 

3 


CONTENTS. 

Page. 

Object  of  sketching 9 

Classification  of  sketches 13 

Outline  for  beginner 14 

Sketching  tools 16 

To  orient  the  board 16 

Conventional  signs 21 

Title 25 

Scales 26 

What  a  sketch  should  show 31 

Horizontal  detail 32 

Traversing 32 

Intersection -. .  32 

Resection » 33 

Estimation ; 33 

Vertical  detail 34 

Contours 35 

Detail  shown  by  contours 36 

Logical  contouring 37 

Contour  framework 40 

Notes  for  field  work 42 

Position  sketch 44 

Adjustment  to  close 45 

Completing  sketch 46 

Outpost  sketch '  46 

Place  sketch 48 

Road  sketch 48 

Reconnaissance  sketches 51 

5 


INTRODUCTION. 

The  writer's  idea  in  publishing  "  Sketching  Methods "  is  to 
simplify  instruction  in  the  subject  and  to  clear  away  the 
mathematics  and  the  mystery  which  seem  to  cling  to  it.  The 
average  student  becomes  confused  because  almost  always  he 
is  required  to  study  map  making  before  he  gets  started  on 
sketching  and  the  result  is  a  jumble  of  ideas  until  he  learns  to 
work  without  instruments.  When  he  learns  this  he  has  learned 
to  sketch.  It  is  thought  that  a  presentation,  in  as  condensed 
form  as  possible,  of  the  methods  developed  by  expert  sketchers 
at  the  Army  Service  Schools  will  be  of  great  assistance  not  only 
to  students  but  also  to  instructors.  The  writer  believes  that 
there  is  no  necessity  for  teaching  the  use  of  the  clinometer  and 
scale  of  slopes  in  order  to  teach  students  how  to  contour.  He 
believes  that  sketching  can  be  taught  more  quickly  and  as  thor- 
oughly by  direct  methods  than  by  indirect  ones.  He  has  tested 
this  belief  and  proved  its  soundness.  In  this  time  of  emergency 
it  is  impossible  to  secure  compasses,  pacetallys,  clinometers, 
tripods,  and  other  expensive  frills  that  have  been  a  part  of 
sketching  for  so  long.  Even  if  they  could  be  procured  there 
would  not  be  time  to  teach  their  use,  for  intensive  training 
means  training  under  pressure  and  that  means  do  away  with 
frills  and  get  down  to  practical  and  direct  methods  of  instruc- 
tion. 

The  student  should  be  taught  what  scales  are,  how  to  make 
conventional  signs  and  their  meaning,  how  to  locate  points  both 
horizontally  and  vertically,  how  to  estimate  differences  of  ele- 
vation of  critical  points,  and  how  to  contour  by  logical  methods 
and  finally  what  is  to  be  shown  on  a  sketch.  He  should  then  be 
given  an  area  to  sketch  in  a  limited  time  for  a  definite  tactical 
purpose.  He  should  be  given  several  such  tasks  to  do,  being 
always  forced  to  work  under  pressure,  and  he  will  rapidly  de- 
velop the  ability  to  sketch. 

There  is  no  reason  why  every  officer  and  noncommissioned 
officer  should  not  learn  to  sketch  and  to  read  sketches  within  a 
very  short  time.  The  instructor  must  thoroughly  understand 

7 


8  INTRODUCTION. 

the  subject.  Common  sense  must  be  his  guide.  His  explana- 
tions must  be  clear  and  simple,  for  the  average  man,  especially 
one  with  a  little  service,  is  looking  for  something  hard  when 
you  mention  sketching  to  him.  A  pencil,  paper,  and  home  made 
ruler  and. board  are  sufficient  tools  for  the  experienced  sketcher 
and  should  be  enough  for  the  beginner. 

W.  C.  SWEENEY. 
PRESIDIO,  SAN  FRANCISCO, 

May  26,  1917. 


MILITARY   SKETCHING. 

OBJECT  OF  SKETCHING. 

Military  sketching  is  an  art.  Its  general  principles  may  be 
learned  from  textbooks,  but  the  mechanical  execution  can  no 
more  be  learned  from  them  than  can  the  art  of  painting. 
The  degree  of  proficiency  attainable  depends  upon  the  intelli- 
gence of  the  sketcher  and  the  amount  of  time  given  to  its 
practice. 

A  map  is  a  projection  to  scale  of  the  topographic  features  of 
the  ground.  It  is  made  with  exact  instruments,  and  its  ac- 
curacy and  completeness  are  the  primary  considerations  in  its 
making. 

A  military  sketch  is  a  report  of  the  topographic  features  of  a 
section  of  country  in  which  certain  conventional  signs  are  used 
as  substitutes  for  words.  Its  accuracy  and  completeness  are 
affected  by  the  "  time  available,"  the  "  instruments  at  hand," 
and  the  "  tactical  conditions "  under  which  the  sketcher  is 
working.  The  difference  between  a  map  and  a  sketch  must 
always  be  in  mind. 

A  report  by  means  of  a  sketch  contains  information  which 
it  is  practically  impossible  to  convey  by  written  words.  Every 
officer,  below  field  rank,  is  liable  to  be  called  upon  at  any  time 
to  make  a  report  on  the  country  under  such  conditions  that  only 
a  sketch  will  answer.  All  officers,  especially  those  of  field  and 
higher  rank,  are  constantly  required  to  read  maps  and  sketches 
and  to  make  tactical  decisions  and  dispositions  based  upon 
them.  The  ability  to  make  a  sketch  guarantees  the  ability  to 
read  and  understand  both  maps  and  sketches.  A  sketcher  finds 
no  difficulty  in  reading  a  map.  Ridge  and  valley  lines  are  at 
once  apparent,  and  he  reads  the  map  easily,  rapidly,  and  under- 
standingly.  A  sketch  is  more  difficult  to  read  than  a  map. 
One  who  is  himself  a  sketcher  has  greater  facility  in  reading  a 
sketch,  because  he  can  grasp  the  sketcher's  meaning  more 
quickly  than  can  one  who  has  never  sketched. 

In  any  well-regulated  scheme  of  instruction  for  military  offi- 
cers, military  sketching  occupies  an  important  and  distinct  place. 
20171°— 17 2  9 


10 


SKETCHING  METHODS. 


The  necessity  for  having  junior  officers  skilled  in  this  art  and 
the  advantages  accruing  from  the  ability  of  field  and  higher 
ranking  officers  to  read  sketches  quickly  are  recognized  every- 


Scale;  l"=  I  mile 


Fig 


where.     In  the  field,  the  report  by  means  of  a  sketch  is  the 
rule,  not  the  exception. 

An  ordinary  use  of  a  sketch  may  be  illustrated  by  the  above 
assumed  situation  (fig.  1). 


SKETCHING  METHODS.  11 

Our  division  is  marching  south,  in  hostile  country,  toward 
an  enemy  who  was  this  morning  reported  to  be  about  20  miles 
south  of  us  and  moving  north.  Our  cavalry  screen  is  4  miles 
south  of  Y.  Our  regiment  forms  the  support  of  the  advance 
guard. 

The  colonel  has  a  map  of  the  country  on  a  scale  of  1  inch  to 
the  mile.  This  map  was  made  several  years  ago.  It  shows 
only  the  flat  detail,  houses,  towns,,  roads,  railroads,  stream 
lines,  trees,  etc.  The  undulations  of  the  country  are  not  shown. 

At  a  halt  along  the  road  the  colonel  calls  to  you,  and,  show- 
ing you  his  map,  says :  "  I  will  arrive  at  Y  at  4.30  p.  m.  to-day 
with  the  point  of  the  advance  guard.  The  division  will  camp 
to-night  at  Dover  and  the  advance  guard  (less  our  regiment) 
about  one-half  mile  south  of  Dover.  Our  regiment  will  form 
the  outpost  on  a  front  from  X  (one-half  mile  west  of  Y)  through 
Y  to  Z  (1  mile  east  of  Y).  Take  four  mounted  orderlies  and 
reconnoiter  from  X  to  Z  and  far  enough  to  the  front  for  out- 
post purposes  and  report  to  me  at  Y  on  my  arrival  there.  I 
want  such  a  report  as  will  enable  me  to  determine  how  best  to 
dispose  the  regiment  for  outpost  duty  without  unnecessary 
delay." 

On  the  colonel's  map  you  saw  that  Y  is  a  crossroad  formed  by 
the  road  over  which  the  division  is  marching  and  the  straight 
X-Z  road. 

You  arrive  at  Y  at  1  p  m.  You  have  three  and  one-half 
hours  in  which  to  make  the  reconnaissance.  You  must  at  once 
recognize  that  only  by  means  of  a  sketch  can  you  gather  and 
convey  the  necessary  information  to  the  colonel. 

At  4.30  p.  m.  you  hand  your  sketch  to  the  colonel  at  Y.  Read- 
ing it,  he  quickly  gains  an  idea  of  the  "  lay  of  the  land  "  and  is 
able  to  dictate  his  order  so  that  his  troops  may  be  marched 
directly  to  their  several  outpost  positions. 

Sketches  vary  in  the  amount  and  value  of  the  information 
that  they  convey  in  exactly  the  same  manner  as  do  written  mes- 
sages and  reports.  The  same  faults  are  found  in  all. 

It  must  always  be  remembered  that  if  there  is  plenty  of  time 
and  conditions  permit,  the  commander  will  send  his  engineers  or 
others  with  accurate  instruments  to  make  a  map  of  the  desired 
area.  As  a  consequence,  sketches  are  made  only  when  there  is 
not  time  to  make  a  map  or  when  conditions  do  not  permit  it. 
The  time  required  to  make  a  sketch  is  always  a  most  important 
factor.  It  will  usually  be  found  that  the  sketch  is  wanted  for 


12  SKETCHING  METHODS. 

use  just  as  soon  as  it  can  be  gotten,  and  often  that  it  is  wanted 
in  such  a  short  time  that  only  an  outline  of  the  desired  area  can 
be  made.  It  is  In  such  a  case  that  the  judgment,  experience, 
and  tactical  training  of  the  sketcher  play  such  an  important 
part.  If  the  sketch  must  be  slighted  in  some  parts  he  must  be 
able  to  determine  what  parts  to  slight  and  where  accuracy  and 
detail  are  necessary,  and  he  can  not  determine  this  unless, 
knowing  the  object  for  which  the  sketch  is  made,  he  realizes 
what  the  commander  needs  to  know  about  the  ground. 

From  the  foregoing  considerations  certain  conclusions  have 
been  deduced  for  the  guidance  of  the  sketcher.  These  may  be 
summarized  as  follows : 

(1)  The  assigned  area  or  distance  should  be  covered  in  the 
time  allotted. 

(2)  Clearness  is  very  important.     No  matter  how  much  valu- 
able information  may  be  gathered,  it  will  be  of  little  use  unless 
it  be  clearly  shown. 

(3)  The  sketch  should  contain  all  data  of  military  value  to 
the  purposes  for  which  it  is  needed.     It  may  be  a  model  in  its 
technique  and  yet  have  left  out  some  feature  of  such  military 
value  as  to  make  it  of  little  or  no  use. 

(4)  A  sketch  may  be  inaccurate  in  many  of  its  measurements 
and  still  be  so  clear  in  showing  what  is  meant  and  have  such 
military  value  that  the  inaccuracies  make  no  difference.    Accu- 
racy, therefore,  though  always  to  be  sought,  must  be  subordi- 
nate in  a  relative  degree  to  finishing  the  task  in  the  time  allotted, 
to  clearness  of  expression,  and  to  military  value. 

The  relative  importance  of  the  foregoing  principles  may  be 
determined  in  each  case  by  a 'careful  summing  up  of  the  require- 
ments of  the  situation  which  calls  for  the  sketch. 

In  the  assumed  situation  cited,  you  should  be  able  to  deter- 
mine at  once  just  what  the  colonel  will  want  to  know  about  the 
area  before  issuing  his  outpost  order.  You  should,  therefore, 
know  what  features  and  distances  to  estimate  and  what  to  meas- 
ure, where  to  go  fast  in  your  work  and  where  to  go  slow. 

Summing  up  the  situation,  you  would  realize — 

(1)  That  the  colonel  will  need  to  have  a  sketch  of  the  whole 
area  before  him. 

(2)  That  the  information  contained  in  the  sketch  must  be  so 
clear  that  there  can  be  no  mistake  about  what  is  meant. 

(3)  That  all  features  which  have  value  in  outpost  duty  should 
be  especially  noted;  for  instance,  a  hill  about  300  yards  south 


SKETCHING  METHODS.  13 

of  Y,  commanding  the  road  from  the  enemy  >  can  be  held  by  com- 
paratively few  men.  The  strength  of  this  position  must  be  indi- 
cated on  the  sketch,  as  it  has  a  direct  bearing  on  the  number 
of  men  assigned  to  the  various  sectors. 

(4)  That  the  sketch  must  be  as  accurate  as  possible,  consistent 
with  (1),  (2),  and  (3). 

There  may  arise  cases  where  the  judgment  of  the  experienced 
sketcher  will  cause  him  to  change  the  relative  value  of  the  fore- 
going principles.  This  is  to  be  expected,  because  each  sketch  is 
a  problem  in  which  the  sketcher  must  use  his  best  judgment  in 
determining  how  to  gain  and  to  convey  the  desired  information. 

The  beginner,  however,  must  learn  to  sketch  before  he  can  pay 
much  attention  to  these  considerations.  Clearness,  accuracy,  and 
speed  in  the  order  named  should  be  his  guide  until  he  has 
attained  a  fair  ability  in  making  a  sketch. 

The  habits  formed  in  learning  to  sketch  will  have  a  great  in- 
fluence upon  the  speed  and  skill  that  may  be  attained.  From 
the  start  system  in  the  methods  of  working  should  be  practiced. 
No  one  can  become  expert  at  sketching  unless  the  habit  of 
working  systematically  is  acquired. 

CLASSIFICATION  OF  SKETCHES. 

The  name  given  usually  indicates  the  nature  of  the  sketch. 
There  are  two  general  classes  of  military  sketches:  (1)  Area 
sketches;  (2)  reconnaissance  sketches. 

Area  sketches  are  classified  as : 

1.  Position  sketch.     This  is  a  sketch  of  an  area  to  all  parts 
of  which  the  sketcher  has  access.    Scale  usually  6  inches  to  the 
mile ;  V.  I.,  10  feet. 

2.  Outpost  sketch.    In  this  the  sketcher  travels  along  and  in 
rear  of  the  outpost  line  sketching  the  area  to  the  front.     Scale 
6  inches  to  the  mile ;  V.  I.,  10  feet. 

3.  Place  sketch.    The  sketcher  is  located  "  in  one  place  "  on  a 
hillside  or  hilltop  in  a  restricted  area,  from  which  he  sketches 
the  area  to  the  flanks  as  well  as  to  the  front.    Scale  6  inches  to 
the  mile  ;  V.  I.,  10  feet. 

Reconnaissance  sketches  are  classified  as : 

1.  Road  sketch.  This  is  usually  made  mounted.  The  sketcher 
preceding  the  column  sends  back  his  reconnaissance  sketches  as 
promptly  as  possible,  so  that  the  commander  may  use  the  in- 
formation contained  in  them  on  the  march  and  in  making  his 
dispositions.  Scale  3  inches  to  the  mile ;  V.  I.,  20  feet. 


14  SKETCHING  METHODS. 

2.  River  reconnaissance  sketch.    This  is  usually  made  with  the 
idea  of  securing  a  special  report  of  topographical  features  and 
other  features  on  a  river  line.    Many  of  these  can  not  be  shown 
by  conventional  signs  and  are  written  on  one  side  of  the  sketch. 
These  sketches  are  made  mounted.    Scale  3  inches  to  the  mile; 
V.  I.,  20  feet. 

3.  Railroad  reconnaissance  sketch.     Similar  to  the  reconnais- 
sance of  a  river.    Scale  3  inches  to  the  mile ;  V.  I.,  20  feet. 

OUTLINE  FOR  BEGINNER. 

The  following  is  a  general  outline  of  the  successive  steps  that 
may  be  taken  in  learning  to  sketch.  It  is  inserted  here  merely  as 
a  guide  to  those  who  are  taking  up  sketching  alone  or  in  com- 
pany 'with  others  who  are  also  beginners.  The  time  available 
to  the  student  must  be  used  to  the  greatest  advantage,  and  he 
alone  is  able  to  divide  it  with  that  in  view.  For  this  reason  the 
steps  are  merely  advisory.  All  indoor  practice  suggested  should 
be  taken  up  and  carried  on  simultaneously  with  field  work. 

In  sketching,  as  in  any  other  art,  practice  only  makes  perfect. 
The  steps  to  be  taken  by  the  beginner  may  be  analyzed  as  fol- 
lows: 

1.  Study  the  conventional  signs  and  practice  same  (p.  21). 

2.  Lay  off  a  measured  ground  course  and  practice  striding  and 
counting  strides  (double  paces)   (p.  17). 

3.  Practice   making   titles   for   different   classes   of  sketches 
(P.  26). 

4.  Determine  stride  and  construct  or  select  scale  of  strides  for 
6  inches  to  1  mile  and  paste  on  ruler  (p.  27). 

5.  Take  out  board  and  practice  orienting  by  turning  arrow  to 
north  and  by  backsighting  (p.  16). 

6.  Practice  location  of  points  by  traversing  and  intersection 
(P- 32). 

7.  Practice  estimating  horizontal  distances  in  units  of  100 
yards  (p.  33). 

8.  Practice  estimating  vertical  distances  in  units  of  10  feet 
(P- 34). 

9.  Run  a  traverse  for  a  short  distance,  putting  in  horizontal 
detail  only.     Practice  locating  points  by  traversing,  intersection, 
resection,  and  estimation  (p.  32). 

10.  Take  up  study  of  contours  and  practice  logical  or  me- 
chanical contouring  (p.  38). 


SKETCHING  METHODS.  15 

11.  Keep  up  practice  in  making  conventional  signs  by  drawing 
imaginary  countrysides  (p.  24). 

12.  Run  a  traverse  again  as  in  figure  9.    Practice  estimating 
differences  in  elevation  between  critical  points  and  noting  same 
(P- 40). 

13.  Make  two  or  three  such  traverses,  practicing  to  acquire 
speed  and  method  in  your  system  of  working  (p.  43). 

Fill  in  only  flat  or  horizontal  detail  but  be  particular  to 
locate  the  drainage  lines.  Practice  orienting  by  back  sight  and 
checking  each  time  by  arrow  pointing  to  north.  Put  a  title  on 
each  before  considering  it  finished  (p.  46). 

14.  Select  an  area  i  to  i  mile  square  and  make  a  sketch  of 
it.     Practice  adjustment  to  close   (p.  45).     Show  all  drainage 
lines  clearly. 

15.  Meanwhile,  having  practiced  logical  contouring  until  you 
can  do  it  intelligently  and  rapidly,  sketch  the  same  area  again 
in  the  same  manner  as  before,  and  in  addition  estimate  and  de- 
termine  elevations   of  critical  points.    Now  take   this   sketch 
and  contour  it  by  logical  methods   (p.  39).     Do  this  at  home 
or  at  some  place  from  which  you  can  not  see  the  ground  you  are 
contouring.     The  idea  of  this  is  to  impress  upon  the  beginner  the 
necessity  of  securing  all  data  that  may  be  needed  for  contouring 
upon  one  traverse  over  the  ground. 

16.  Make  another  sketch  of  the  same  area.    Fill  in  flat  detail 
as  you  go  and  note  elevation  and  location  of  critical  points. 
When  you  have  the  drainage  system  clearly  plotted,  contour  the 
sketch  on  the  ground.     Space  the   contours  according  to  the 
ground  (p.  41). 

17.  Make  position  sketches  of  other  areas  in  the  same  manner 
as  the  last  one  (p.  45).    Never  start  contouring  until  the  drain- 
age system  is  "  pinned  down " ;  the  big  features  will  then  be 
seen,  and  the  little  ones  will  take  care  of  themselves. 

18.  Make   at   least   three   outpost   sketches    and   two   place 
sketches  at  6  inches  to  the  mile  and  10  feet  V.  I.  before  attempt- 
ing to  make  a  road  sketch  (p.  46). 

19.  Construct  a  scale  of  strides  for  3  inches  to  the  mile  and 
take  up  road  sketching  dismounted  (p.  48). 

20.  Secure  a  mount  and  make  a  scale  reading  minutes  for  trot 
and  walk.    Take  up  mounted  road  sketching  (p.  50). 

21.  Later  take  up  other  kinds  of  reconnaissance  sketching 
(p.  51). 


16  SKETCHING  METH.ODS. 

SKETCHING  TOOLS. 

Sketching  board. — The  issue  sketching  board  with  a  com- 
pass set  in  a  trough  in  one  edge  is  a  good  board  for  sketching. 
It  has  an  attachment  on  the  under  side  for  securing  the  tripod 
to  it.  It  is  about  13  by  14  inches,  which  allows  2  miles  of  posi- 
tion sketch  (6  inches  to  the  mile)  to  be  made  with  enough  extra 
space  to  secure  the  paper  to  the  board. 

A  homemade  board  of  the  same  size,  made  of  light  wood 
about  seven-eighth  inch  thick,  with  holes  in  two  diagonally 
opposite  corners  for  a  rope  by  which  to  carry  it,  makes  a  very 
good  sketching  board. 

A  tripod  may  be  used,  but  is  not  necessary.  When  instructing 
large  classes  by  intensive  methods  the  compass,  pace  tally,  and 
tripod  should  not  be  used,  as  it  requires  too  much  time  to  learn 
their  use. 

TO  ORIENT  THE  BOARD. 

Having  tripod  and  compass. — Set  up  the  tripod  with  board 
loosely  screwed  on  to  it  and  level  by  eye  by  moving  the  tripod 
legs.  Note  that  tripod  legs  are  firmly  set  so  as  not  to  slip 
easily.  Free  the  needle  by  turning  the  cam  and  then  turn  the 
board  slowly  around  until  the  needle  swings  from  side  to  side 
in  the  trough.  Let  the  needle  settle,  turning  the  board  so  that 
when  settled  the  needle  lies  directly  over  the  north  line  in  the 
bottom  of  the  trough.  Without  changing  the  position  of  the 
board,  reach  under  and  tighten  up  the  screw  of  the  tripod.  Care 
must  always  be  taken  not  to  turn  the  tripod  screw  too  tight,  as 
the  threads  are  likely  to  be  started  by  rough  treatment.  The 
board  is  now  oriented.  Draw  a  line  parallel  to  the  needle  on 
the  paper  and'  mark  the  north  end  with  a  half  arrow.  This 
magnetic  meridian  line  is  sometimes  marked  M.  M. 

Without  compass  and  tripod. — Draw  a  line  parallel  to  the 
edge  of  the  paper  and  place  a  half  arrow  on  one  end  of  it.  Turn 
the  board  around  until  the  arrow  points  north  and  the  board  is 
oriented.  Use  watch  and  sun  or  general  knowledge  to  determine 
north  at  first ;  thereafter  orient  by  backsight,  but  check  back- 
sight orientation  when  necessary  by  the  same  methods. 

To  orient  the  board  by  backsight. — Having  plotted  (located 
and  drawn  in)  a  station  and  arrived  at  a  point  farther  on, 
which  you  have  sighted  and  drawn  a  line  to,  measure  off  the 
number  of  strides  taken  between  the  two  points  on  your  line 


SKETCHING  METHODS.  17 

and  stick  a  pin  in  the  point  found.  This  is  your  present  posi- 
tion. Place  your  ruler  against  the  pin  and  along  the  line  be- 
tween the  two  points,  and  turn  the  board  until  the  station 
which  you  have  just  left  is  sighted.  The  board  is  oriented. 
Verify  this  by  checking  arrow  or  reading  the  compass  needle. 

All  of  these  methods  of  orientation  can  be  practiced  in  a 
small  space.  Set  up  the  board  and  orient  by  compass.  Stick  a 
pin  in  your  assumed  position  and  draw  to  a  fence  post  or  any 
object  15,  20,  or  100  feet  distant.  Now  move  over  to  near  the 
fence  post  and  set  up  again.  Orient  the  board  by  arrow  and 
then  verify  by  a  backsight  orientation  on  the  first  station.  For 
this  practice  a  scale  of  an  inch  to  a  few  feet  may  be  assumed 
and  the  distances  measured.  In  this  case  practice  may  be  had 
from  one  point  to  three  others  and  then  back  to  the  first.  This 
will  give  an  opportunity  to  check  the  accuracy  of  your  orienta- 
tion by  seeing  how  well  your  lines  close.  Intersection  and  resec- 
tion methods  may  also  be  practiced  in  this  same  manner. 

Tally  register  or  pace  tally. — This  instrument  is  used  to  keep 
the  record  of  the  number  of  strides  (double  paces)  taken  in 
measuring  the  distance  between  points.  It  is  important  that  the 
number  of  strides  be  counted  as  accurately  as  possible,  and  for 
this  reason  the  beginner  should  learn  to  register  them  auto- 
matically ;  that  is,  without  giving  the  act  of  pressing  the  lever 
any  attention. 

With  the  pace  tally  held  in  the  left  hand,  finger  through  ring, 
the  lever  is  pushed  down  each  time  the  right  foot  strikes  the 
ground.  This  system  of  recording  the  strides  is  the  best  pos- 
sible, because  the  left  hand  is  free  to  handle  the  register  and 
after  practice  will  automatically  or  subconsciously  press  the 
lever  when  the  right  foot  strikes  the  ground,  which  occurs  when 
the  left  hand  reaches  the  forward  point  of  its  swing.  The  more 
nearly  automatic  the  act  of  recording  the  strides  becomes,  the 
more  can  the  sketcher's  attention  be  given  to  observing  the  con- 
figuration of  the  ground  and  the  details  of  the  country  through 
which  he  is  passing. 

However,  it  is  possible  to  get  very  good  results  by  training 
men  to  count  their  strides  and  tally  every  100  strides  on  the  edge 
of  the  paper.  There  are  various  ways  of  counting  and  tallying 
strides  without  a  pace  tally.  After  a  little  practice  each  indi- 
vidual will  select  his  own  way.  The  beginner  should  learn  to 
stride  at  a  uniform  gait  and  to  register  the  strides  or  to  count 
them  with  the  least  mental  effort.  Do  not  attempt  to  take 
20171° — 17 3 


18  SKETCHING  METHODS. 

strides  of  a  certain  length,  but  step  along  at  a  natural  gait, 
swinging  the  arms  naturally  and  keeping  the  mind  off  of  the 
counting  of  strides  or  of  their  length.  When  walking  anywhere 
by  yourself  practice  counting  your  strides  or  carry  the  pace  tally 
and  register  them.  If  opportunity  offers  do  this  in  walking  to 
or  from  your  office  or  place  of  business.  Practice  it  as  much  as 
possible,  and  you  will  soon  find  that  the  number  of  strides  in  a 
given  distance  will  become  more  and  more  uniform.  Until  one 
learns  to  stride  naturally  and  uniformly  the  stride  will  be 
affected  by  walking  with  or  near  another  person. 

Once  in  a  while  a  tally  register  will  be  found  which  occa- 
sionally fails  to  register  a  change  of  100  strides.  This  can  be 
detected  by  a  peculiar  click  when  it  happens.  The  failure  is 
often  due  to  the  sketcher  not  pressing  the  lever  down  far 
enough.  The  register  can  be  tested  indoors  by  watching  the 
face  of  the  dial  wrhile  pressing  the  lever  and  tallying  through 
a  couple  of  hundred  counts. 


, 

milll  im  liiiiliiiiliiiillliiliiiiliiill  1 1 1 1 1 1 1  ilii 


ng.  a 

Triangular  ruler  (fly.  2). — The  best  ruler  for  sketching  is  one 
of  triangular  shape  about  8  inches  long  with  faces  about  0.8 
inch  wide,  with  both  ends  weighted.  Such  a  ruler  has  been  de- 
veloped at  the  Army  Service  Schools  and  can  be  bought  at  slight 
expense  from  the  Book  Department,  Army  Service  Schools,  Fort 
Leavenworth,  Kans.  It  has  on  it  a  scale  of  inches,  one  of  100 
yards  at  3  inches  to  the  mile,  and  one  of  100  yards  at  6  inches 
to  the  mile.  There  is  ample  space  left  on  which  the  sketcher 
may  paste  his  scale  of  strides  for  sketching  at  6  inches  and  at  3 
inches  to  the  mile,  as  well  as  his  horse's  walk  and  trot  scale 
for  mounted  work.  A  very  satisfactory  ruler  can  be  made  by 
sawing  in  two  a  piece  of  pine  or  other  common  wood  about 
seven-eighths  inch  square.  This  makes  a  triangular  ruler  which 
is  convenient  in  size  and  shape.  It  should  be  cut  in  6-inch 
lengths  and  should  have  on  it  the  sketcher's  scale  of  strides,  a 
scale  reading  100  yards  at  6  and  at  3  inches  to  the  mile  and  an 
inch  scale  reading  down  to  a  tenth  of  an  inch. 


SKETCHING  METHODS.    t  19 

When  using  the  ruler  for  sighting  an  object,  place  one  of  the 
edges  against  the  pin  in  your  station,  sight  along  the  top  edge, 
and  pivot  the  ruler  with  forefinger  and  thumb  around  the  pin 
until  the  desired  object  is  in  line.  Then  draw  the  ray  (light 
line)  along  the  edge  of  the  ruler  next  to  the  pin.  When  sighting 
up  or  down  a  steep  slope,  the  sketcher  may  find  it  of  assistance 
to  stick  a  pin  vertically  in  each  end  of  the  top  edge  and  use  them 
to  sight  by. 

Pencils. — A  soft  pencil,  HB  grade,  or  Eberhard  Faber  No.  2 
with  eraser  on  it,  should  be  used  in  learning  to  sketch.  Harder 
pencils  will  tear  the  paper,  and  their  marks  are  so  difficult  to  see 
that  the  sketcher  is  likely  to  strain  his  eyes.  When  sheet  cellu- 
loid is  used,  a  2H  pencil  is  better. 

A  knife  or  a  pencil  sharpener  should  be  carried,  and  the  pen- 
cils should  always  be  kept  sharp.  A  piece  of  emery  paper  pinned 
to  the  carrier  is  very  valuable  for  putting  on  a  finished  point. 

Eraser. — A  soft  rubber  eraser  is  a  popular  article  in  the  equip- 
ment of  the  beginner.  The  Ruby,  Eberhard  Faber,  New  York,  is 
a  very  satisfactory  one.  One  on  the  pencil  will  serve,  however, 
very  nicely. 

Paper  and  thumb  tacks. — All  sketches  should  be  made  on  a 
tracing  paper  in  order  that  they  may  be  blue  printed  without 
the  necessity  of  tracing  them.  For  this  reason  tracing  paper 
should  always  be  used,  except  in  the  earlier  practice  when  any 
variety  of  drawing  or  heavy  wrapping  paper  will  do.  It  will 
be  found  that  the  paper,  if  pinned  to  the  board  by  thumb  tacks 
some  time  before  it  is  to  be  used,  will  bulge  up  and  have  to  be 
readjusted.  For  this  reason  it  is  well  not  to  pin  your  paper 
in  position  until  just  before  starting  out.  Extra  thumb  tacks 
should  be  carried.  These  may  be  stuck  on  the  under  side  of  the 
board  or  kept  in  a  piece  of  cork  in  the  carrier. 

Large-headed  pins. — Several  of  these  should  be  stuck  in  the 
carrier  or  clothing  where  they  can  be  gotten  at  conveniently. 
They  are  most  useful  in  sketching.  Common  glass-headed  pins 
about  1|  inches  long  with  a  head  about  one-tenth  inch  in  diam- 
eter are  best. 

Carrier. — This  can  be  made  of  canvas  or  heavy  cloth  sewed 
over  a  piece  of  light  wood  or  heavy  cardboard,  or  they  may  be 
purchased  at  the  Book  Department,  Army  Service  Schools 
(fig.  3).  The  sketcher  must  have  every  appliance  in  its  place 
when  he  wants  to  use  it,  arid  the  carrier  offers  a  most  con- 


20 


SKETCHING  METHODS. 

The  carrier,  however, 


venient  place  for  nearly  all  of  his  tools. 
is  not  necessary. 

Stop  watch\  and  note  pad  for  mounted  work  (fig.  4). — These 
are  very  convenient  for  mounted  work.  The  pad  is  divided  into 
blocks.  The  middle  line  from  the  bottom  up  represents  the 
sketcher's  route  by  minutes  and  quarter  minutes  of  travel,  while 
the  horizontal  lines  to  the  sides  represent  hundreds  of  yards, 


Fig.  3 


off  from  the  sketcher's  route.  As  the  horse  trots  along  the 
road,  the  sketcher  jots  down  on  the  pad  in  their  proper  places 
the  various  features  which  he  observes.  After  some  minutes  of 
travel,  he  dismounts,  and,  using  these  notes,  sketches  in  the 
road  over  which  he  has  passed.  It  is  well  in  making  notes  on 
the  pad  to  use  a  blue  pencil  for  noting  water  courses  and  hori- 
zontal details  and  a  red  one  for  carrying  along  the  elevations. 
A  pencil  with  red  at  one  end  and  blue  at  the  other  can  be  pur- 
chased at  any  bookstore. 


SKETCHING  METHODS.  21 

CONVENTIONAL  SIGNS. 

The  conventional  signs  used  in  military  sketching  are  illus- 
trated in  Field  Service  Regulations. 

In  practical  sketching,  if  it  is  more  difficult  or  requires  more 
time  to  make  the  conventional  sign  than  it  does  to  write  what 
is  meant,  the  experienced  sketcher  will  write  the  description. 

A  sketch  is  made  primarily  to  convey  certain  information. 
If  what  is  meant  to  be  conveyed  is  not  clear  the  sketch  is  of 
no  use.  Again,  if  it  takes  a  commander  too  long  to  read  a 
sketch  he  will  blame  the  sketcher,  and  as  his  time  will  probably 
be  valuable  he  may  not  be  able  to  take  time  to  read  it.  Always 
remember  that  the  sketch  is  being  made  to  be  read,  that  the 
convenience  of  the  reader  is  sought,  not  that  of  the  sketcher, 
that  it  is  useless  to  put  a  mark  on  the  sketch  unless  that  mark 
has  a  meaning  which  the  reader  will  be  able  to  make  out. 

It  is  desirable  that  the  conventional  signs  shall  picture  what 
they  represent  as  nearly  as  possible,  so  as  to  be  easily  inter- 
preted ;  be  simple  in  construction  so  that  they  may  be  made 
rapidly ;  not  take  too  much  space  on  the  sketch ;  and  that  they 
be  so  clear  as  to  be  readily  understood  and  not  be  mistaken 
one  for  another. 

Practice  in  rapid  work  has  developed  many  short  cuts  in 
making  them.  These  convey  the  same  information  with  fewer 
pencil  marks  and  probably  greater  clearness  (fig.  5). 

It  is  to  be  noted  that  the  cross  marks  on  a  railroad,  the 
signs  indicating  the  different  kinds  of  fences,  the  marks  along 
a  road  indicating  telegraph  line  and  the  T  representing  a  tele- 
graph line  across-  country,  are  to  be  made  1  inch  to  1J  inches 
apart  on  a  scale  of  3  or  6  inches  to  the  mile.  This  is  done  prin- 
cipally for  the  sake  of  clearness,  though  a  great  deal  of  time 
is  saved  by  it.  It  is,  however,  an  excellent  rule  never  to  put 
a  mark  on  a  sketch,  no  matter  how  small,  that  is  not  necessary. 

A  culvert  or  bridge  less  than  10  feet  long  (road  length)  should 
be  represented  by  two  V's  at  right  angles  to  the  road,  with  the 
points  of  the  V's  opposite  each  other.  Dimensions  need  not  then 
be  given  as  in  a  larger  bridge,  but  the  material  and  the  condi- 
tion, if  poor,  should  be  noted,  "  brick,  poor,"  or  "  wood,  bad." 

Roads  are  conventional  signs.  Try  and  show  them  about  one- 
sixteenth  of  an  inch  wide  at  3  inches  to  the  mile  and  about  one- 
tenth  inch  wide  at  scale  of  6  inches  to  the  mile.  The  road 
lines  should  stand  out  clear  and  distinct,  with  no  lines  or  other 


22 


SKETCHING  METHODS. 


conventional  signs  crossing  the  road.     Fence  and  telegraph  signs 
are  placed  on  the  road  lines. 


\    Cut    10-   / 


IVoad.. /Smooth  and  Bar 
-bedWire  Fences.  Cut 


-H- 


t  Fa""    ^.. 


T 


_  Road. He dj}e  Fence  Tele- 
graph. Fill " 

_     Culvert. Bridge  with 
-  Dirrienaions. 


S.D  *  A  TVR. 

H 1 


1 Railroad  Rxsjht  of 

Fence  Ma\)  Be  Shown  or 
^_Note  Stating  it  is  There 


Be  Made  iy\ 


x     Barbed  Wire    Fence 
Across  Coun*r>j  . 
TeX.Lvne  Off   Road. 

NX^oods   \  Area  Covered  by  Woods 


•Stream  Line  Zo'  Wide 
2o'wo      8* Banks  2' Deep. 

^  Scattered  Trees  on  all 

one  Branch 
Broken  Line  s  no  Water 


Stone 

I  Mouse  6'-i  Mile 
Mouse  3-1  Mile 


Where  Area  is 
Not  Cultivated 
Leave  Blank 


i.  5 


A  hedge  fence  is  represented  by  drawing  H's  across  one  of  the 
road  lines  at  about  the  same  intervals  as  fence  signs.     Fence  and 


SKETCHING  METHODS.  23 

hedge  signs  are  the  only  marks  that  should  ever  appear  between 
the  borders  of  a  road. 

Stone  and  wood  fences,  being  very  unusual  features,  are  noted 
in  sketching  by  writing  in  "  stone  "  or  "  wood  "  along  a  line 
drawn  to  represent  the  fence ;  if  along  a  road  use  the  road  line, 
with  marks  indicating  the  limits  of  the  stone  or  wood  fence.  A 
marginal  note  is  simplest  and  easiest. 

Signs  for  single  trees  are  drawn  oblong  in  shape  and  about 
one-tenth  of  an  inch  long  at  6  and  about  one-sixteenth  inch 
long  at  3  inches  to  the  mile.  Space  them  sufficiently  to  be  dis- 
tinct so  as  to  blue  print  readily.  Do  not  attempt  to  show  indi- 
vidual trees.  The  sign  indicates  trees  in  that  locality. 

Houses  are  represented  by  black  blocks  which  are  made  square 
and  large  enough  to  be  set  in  the  road  at  the  scale  being  used. 
That  will  make  the  house  sign  about  one-tenth  inch  square  at 
6  and  one-sixteenth  inch  square  at.  3  inches  to  the  mile. 

In  order  to  proportion  the  signs  to  the  scale  used  it  is  conven- 
ient to  always  make  the  lines  that  go  on  or  along  the  road  about  as 
long  as  the  road  is  wide.  This  refers  to  such  signs  as  a  telegraph 
line  along  the  road,  the  barbed-wire  fence  lines  which  make  the 
X's  on  a  road  line,  and  the  signs  for  cuts,  fills,  bridges,  cul- 
verts, etc. 

A  row  of  houses  occupying  a  certain  distance  along  a  road 
need  not  be  indicated  individually,  but  house  signs  covering  the 
scale  distance  occupied  by  them  should  be  drawn  in. 

A  dry  watercourse  should  be  indicated  by  a  broken  line, 
which  should  be  wavy  so  as  not  to  be  mistaken  for  a  trail  sign, 
which  is  a  broken  straight  line.  If  there  is  a  small  town  along 
your  road,  do  not  attempt  in  a  road  sketch  to  show  the  indi- 
vidual streets,  alleys,  and  houses,  but  make  a  town  sign  cover- 
ing the  area  of  the  town,  and  write  in  its  name.  (See  fig.  1, 
town  of  Dover.) 

Where  the  conventional  sign  or  written  words  can  not  be  put 
in  at  the  place  desired  without  excessive  crowding,  write  a  (1) 
at  that  place  and  insert  description  in  a  marginal  note  opposite 
a  (1)  on  the  margin.  Carry  these  marginal  notes  by  serial 
numbers ;  on  a  road  sketch,  start  them  at  the  bottom  of  the 
margin  and  run  up ;  on  other  sketches,  start  at  the  top  of  the 
paper  and  number  them  down. 

Break  contour  lines  on  each  side  of  a  road,  a  conventional 
sign,  or  an  abbreviation  (as  a  description  of  a  bridge).  Never 
run  them  through. 


24  SKETCHING  METHODS. 

It  should  be  remembered  that  your  sketch,  when  finished, 
must  be  ready  for  blue  printing  copies  without  tracing ;  therefore 
all  signs  should  be  distinct  enough  for  this  purpose.  All  lines 
should  be  firm  and  clear  cut. 

Anyone  who  has  the  ability  to  learn  to  read  and  write  should 
be  able  to  learn  to  sketch.  In  sketching,  as  in  writing,  how- 
ever, the  signs  used  have  to  be  learned,  and  facility  in  making 
them  has  to  be  gained  before  much  can  be  accomplished.  Much 
time  is  wasted  in  the  field  by  beginners  on  account  of  the  fact 
that  they  have  not  sufficient  familiarity  with  the  conventional 
signs  and  abbreviations  to  enable  them  to  put  down  the  right 
one  quickly.  No  one  should  attempt  to  sketch  until  the  conven- 
tional signs  are  learned  and  some  facility  in  making  them  has 
been  acquired.  This  can  be  practiced  anywhere  indoors  by 
drawing  a  skeleton  sketch  of  roads  and  stream  lines  and  filling 
in  imaginary  countrysides.  Locate  and  draw  in  farmhouses, 
orchards,  fences,  trees,  woods,  cuts,  fills,  bridges,  unimproved 
roads,  railroads,  etc.  Form  a  general  idea  of  scale  distances,  but 
make  this  practice  mainly  to  help  you  to  learn  the  conventional 
signs  so  that  when  you  see  something  that  you  wish  to  repre- 
sent, you  will  be  able  to  put  it  down  without  having  to  stop  and 
think  how  you  should  represent  it.  It  is  splendid  practice  for 
a  class  to  have  the  instructor  dictate  to  them  a  description  of  a 
countryside  which  the  students  represent  by  conventional  signs 
at  the  scale  ordered.  The  various  features  and  objects  are  rep- 
resented according  to  the  distance  and  direction  as  given  by 
the  instructor.  To  stimulate  interest  and  note  progress  the 
papers  may  be  turned  in  and  corrected.  It  is  not  only  neces- 
sary to  know  the  sign  when  you  see  it,  but  it  is  necessary  in 
sketching  that  you  be  able  to  make  it  quickly  and  easily.  It 
should  be  easier  for  the  sketcher  to  make  the  conventional  sign 
than  to  write  the  words.  Practice  of  this  kind  will  also  assist 
in  overcoming  the  diffidence  that  many  feel  about  the  mechanical 
work  of  drawing,  as  it  will  accustom  the  hand  and  eye  to  work- 
ing with  pencil  and  ruler. 

A  familiarity  with  the  scale  distance  of  some  commonly  used 
unit  of  measure  is  essential  to  the  sketcher  for  putting  down 
distances  as  he  estimates  them.  All  estimates  of  distance 
should  be  made  in  hundreds  of  yards;  therefore  the  sketcher 
should  be  able  to  accurately  lay  off  a  100-yard  measure  to  the 
scale  of  the  map.  As  all  work  in  learning  to  sketch  will  be  at 
6  and  3  inch  scales,  the  beginner  should  practice,  along  with 


SKETCHING  METHODS.  25 

the  making  of  conventional  signs,  jotting  down  hundreds  of 
yards  at  6  and  3  inches  to  the  mile  and  inches  and  halves  and 
tenths  of  inches.  This  can  be  done  by  dotting  off  these  dis- 
tances any  time  or  anywhere  and  then  checking  them  with 
those  found  on  the  triangular  ruler.  This  also  gives  an  idea  of 
what  may  be  shown  at  the  different  scales.  At  scale  of  1  inch 
to  the  mile  a  heavy  pencil  line  is  about  50  yards  wide ;  one- 
tenth  inch  at  6  inches  to  the  mile  is  about  30  yards ;  at  3  inches 
to  the  mile  it  is  60  yards;  and  at  12  inches  about  15  yards. 
This  practice  is  most  important  for  the  beginner. 

TITLE. 

Every  completed  sketch  should  contain  a  title,  setting  forth 
the  character  of  the  sketch,  the  sketcher's  name  and  rank,  the 
locality  sketched,  the  date,  the  scale  (in  inches  to  the  mile),  a 
graphic  reading  scale  of  yards,  and  the  north  and  south  line 
parallel  to  one  side. 


POSIT/ON  SKETCH 

Near  Ea  start 

By  W*  SmH-h,Cap+.  2nd In f 
May  15  19/5 

6"  -  I  mile 
Yards 


Fig.  & 

All  lettering  on  position  sketches  should  be  written  so  as  to 
be  read  from  the  south  edge.  In  place  sketches  it  should  be  so 
located  as  to  be  read  from  the  sketcher's  position  with  the 
sketch  oriented.  In  outpost  sketches  the  lettering  is  read  fac- 
ing toward  the  enemy.  In  road  sketches  the  lettering  should 
be  made  so  that  it  may  be  read  by  anyone  following  the  route 
of  the  sketcher  with  the  sketch  oriented. 

Figure  6  illustrates  the  title  for  a  position  sketch.    In  another 
kind  of  a  sketch  the  proper  name  and  scale  is  substituted. 
20171°— 17 4 


26  SKETCHING  METHODS. 

Printed  letters  are  so  much  clearer  than  ordinary  longhand 
writing  that  they  should  always  be  used  in  the  body  of  the 
sketch  and,  where  time  permits,  in  marginal  notes.  In  recon- 
naissance sketches  there  will  be  so  many  marginal  notes  that 
it  is  usually  impracticable  to  print  them  and  they  are  therefore 
written  out  in  longhand. 

Contour  numbers  should  also  be  placed,  as  far  as  possible, 
the  same  as  the  lettering.  See  figures  10  and  11. 

Time  is  saved  and  the  chances  of  omissions  avoided  by  block- 
ing out  on  heavy  cardboard  a  completed  title  like  the  one  in 
figure  6,  and  keeping  it  in  the  back  part  of  the  carrier.  This 
can  be  slipped  under  the  paper  on  the  board  and  traced. 

In  a  road  sketch  put  the  title  at  any  convenient  place.  In 
all  other  sketches  place  it  so  as  to  be  read  from  the  south 
edge. 

Where  the  V.  I.  used  is  different  from  that  prescribed  in  the 
normal  system  of  scales  (p.  34),  it  should  be  noted  in  the 
title. 

SCALES. 

It  is  usual  in  military  work  to  speak  of  the  scale  of  a  map 
or  sketch  by  stating  the  number  of  inches  on  it.  which  repre- 
sent 1  mile  on  the  ground.  Thus  we  say  a  certain  sketch  is 
made  on  a  scale  of  3  inches  to  the  mile,  meaning  that  3  inches 
on  the  sketch  represents  1  mile  on  the  ground. 

A  scale  may  be  expressed  in  three  ways,  any  one  of  which 
is  sufficient  to  acquaint  the  reader  with  it.  These  three  ways 
are: 

1.  By  expression  in  words  and  figures:  3  inches  equal  1  mile. 
G  inches  equal  1  mile. 

2.  By  what  is  known  as  the  "  representative  fraction."     This 
is  abbreviated  as  "  R.  F."    The  fraction  expresses  map  distance 
in   its   enumerator   and   corresponding   ground    distance   in    its 
denominator.     For  example,  the  R.  F.  of  a  map  on  a  scale  of 
3  inches  to  the  mile  would  be  written  R.  F.   =21j20.     The 
numerator  is  always  reduced  to  unity.    One  (unit  of  measure) 
on  the  map  represents  21,120  (of  the  same  units  of  measure) 
on   the   ground.     The   scale   in    inches   to   the   mile    is   ivadily 
found  by  dividing  the  denominator,  21,120,  into  the  number  of 
inches  in  a  mile,  63,360.    This  scale  is  seldom  used  in  sketching. 
Its  use  is  mainly  in  case  of  making  a  sketch  which  maybe 
converted  into  some  foreign  unit  of  measure. 


SKETCHING  METHODS.  27 

3.  By  a  graphic  scale.  This  is  a  line  drawn  on  the  map  or 
sketch  and  divided  into  equal  parts.  Each  of  these  is  marked 
with  the  number  of  ground  units  it  represents.  In  our  service 
it  is  usual  to  make  these  divisions  read  miles  and  halves  and 
quarters  of  miles  when  expressing  the  scale  graphically.  This 
scale  is  useful  on  maps  which  are  to  be  increased  or  reduced 
by  photography,  on  account  of  the  fact  that  it  will  always  read 
true. 

There  are  two  other  kinds  of  graphic  scales — reading  and 
working.  The  reading  scale  is  made  to  read  some  well-known 
and  commonly  used  unit  of  measure,  as  feet,  yards,  etc.  In 
military  sketches  it  is  made  to  read  yards.  To  construct  a 
reading  scale  at  a  scale  of  6  inches  to  1  mile,  lay  off  a  couple 
of  inches  of  length  and  divide  each  inch  into  three  parts.  Each 
part  will  then  represent  100  yards.  At  that  scale  0.346  inch 
represents  100  yards,  and  that  is  as  near  one-third  of  an  inch 
as  it  can  be  drawn  with  an  ordinary  pencil.  After  dividing  the 
inches  into  thirds  divide  the  left  division  into  four  parts,  each 
of  which  will  represent  25  yards.  Mark  off  the  main  scale  to 
read  hundreds  of  yards.  For  sketching  purposes  1  mile  may 
be  said  to  contain  1,800  yards.  At  scale  of  6  inches  to  1  mile 
1  inch  will  equal  300  yards  and  one-third  inch  will  equal  100 
yards. 

The  working  scale  is  made  to  read  the  units  of  measure  used  in 
making  the  sketch.  In  sketching  this  is  usually  strides  (double 
pace)  for  dismounted  work,  and  minutes  of  travel  of  horse  at 
trot  and  walk  for  mounted  work.  The  completed  military 
sketch  should  contain  the  scale  expressed  in  words  and  figures, 
as  6  inches=l  mile,  and  a  reading  scale  to  read  hundreds  of 
yards.  The  working  scale  should  not  appear  on  the  sketch. 

It  is  not  essential  that  the  sketcher  should  have  to  do  the 
mechanical  drawing  in  connection  with  the  construction  of  his 
working  scale.  He  should  know  how  to  do  it  in  case  of  need. 
Scales  for  any  length  of  stride  or  minute  scales  for  a  horse  at 
trot  and  walk  at  any  desired  scale  can  be  secured  from  the 
Book  Department,  Army  Service  Schools,  at  Fort  Leaveuworth. 

Stride  scales  for  6  inches  to  1  mile  are  printed  in  figure  7. 
They  are  placed  here  for  convenience.  To  use  one  of  them  the 
sketcher  must  first  carefully  determine  the  length  of  his  stride 
and  either  cut  out  the  scale  for  his  length  of  stride  or  lay  off 
the  divisions  on  another  paper  and  paste  on  his  ruler.  Assume 
that  the  average  number  of  strides  taken  by  the  sketcher  over 
a  1-mile  measured  course  is  1,048.  To  determine  the  length  of 


28  SKETCHING  METHODS. 

stride  divide  63.360  (the  number  of  inches  in  1  mile)  by  1.048, 
and  the  quotient,  60.4,  will  be  the  number  of  inches  in  one 

Fig.  7 

0  1  2 3    inc"hes 

SCALE  OF  STRIDES 
6"  =  1  MILE 

P""  "  ''I1'")  "  "[  i  |  II  |  I  I  II  [I  II  I  [I  I  Illl  II  1-|  II  H  [I  I  H[  Mill  II 
0      6O  INCH  STRIDES      2  4-  o 


II  1  1  I  |  M  I  I  1  1  I  I  I  [  I  I  I  1  1  I  M  I  |  I  I  I  1  1  1  1  1  1  1  1  1  I  I  [I  I  I  I  |  I  I  I  I  I  I  I  I  i  1  1  i  i  I  i  I  I 
®      61  INCH  STRIDES       ^  4 

1  1  i  I  I  |  I  I  I  I  1  1  I  I  I  |  i  I  I  I  I  I  I  I  I  |  I  I  II  [  I  I  I  I  1  1  I  I  I  1  1  I  I  I  |  I  I  1  1  1  1  I  I  I  [  I  I  i  1  1  i 
Q       62  INCH  STRIDES      246 

III  I  i  |  i  i  I  I  [  I  I  I  I  |  I  I  I  I  I  I  I  I  I  [  i  I  i  |  I  I  1  1  |  )  i  i  j  I  I  I  I  I  I  |  I  I  1  i  I  i  i  I  i  |  1  1  i  i  i 
"       63  INCH  STRIDES      2  4  6 


1  I  i  i  i  i  I  i  i  i  i  ;  I  i  j  ;  i  •  i  MI  1  1  |  I  I  |  I  [  i  I  I  1  1  1  i  I  i  |  i  i  I  i  1  1  i  i  i  i 
2  4t 


64  INCH  STRIDES 


I  I  I  M  |  i  I  I  I  I  I  I  I  M  I  i  I  I  I  I  I  I  I  |  I  I  I  f  J.I  I  I  i  |  M  I  I  I  I  I  I  I  |  I  I  I  I  I  I  I  I  I  M  ' 

0  65  INCH  STRIDES       *•  4 

1  in  I  |  i  I  I  I  I  I  I  I  I  |  I  I  I  I  I  i  I  M  |  I  I  I  I  I  I  I  I    |  I  I  I  I  I  I  I  M  |  I  I  i  i  |  i  i  ii  |  M 
f\  t>  /. 

v'       66  INCH  STRIDES        - 

inii|innii!iiiiiiMi  ......  HIIIMIIUJHMI  nii|iiii  it 

0  67  INCH  STRIDES        ^ 

Mi  i  i  |  i  ii  i  [  i  i  I  i  |  i  I  i  it  ii  il  |  I  |  |  ij|  MM  i  i  i  ijni  i  I  I  I  I  I  |  I  I  I  I  I 
0         68  INCH  STRIDES         2  •* 

1  i  I  i  I  |  j  U  I  [  I  I  I  !  J  I  I  I  I  II  I  i  I  |  I  I  I  I  I  I  I  I  I  M  I  I  LM  i  I  I  |  I  I  H  [  I  I  l  1, 
"          69  INCH  STRIDES        *  ^^%-^^^ 


|  1  I    I    I   1  I        I  I    I    I        I    I   I    I        I    '    ! 


0         70  INCH  STRIDES         2  4 

•< 

stride.    Select  the  scale  reading  nearest  to  the  length  found.    In 
this  case  60  inches  would  be  taken  as  the  stride. 


.'•>  ^&: 


SKETCHING  METHODS.  2S 

Scales  constructed  by  the  student  should  be  made  in  ink  and, 
when  dry,  pasted  on  to  the  ruler  and  later  given  a  coat  of  shellac 
to  make  them  waterproof. 

It  is  very  important  that  the  sketcher  develop  a  uniform  stride 
and  that  the  strides  be  accurately  counted.  To  accomplish  this 
is  the  most  difficult  part  of  scale  making.  The  average  number 
of  strides  over  a  given  distance  must  be  fairly  uniform,  or  the 
working  scale,  no  matter  how  accurately  constructed,  will  not 
be  of  much  use. 

Every  sketcher  must  have  a  working  scale,  constructed  to  read 
strides,  at  6  inches  to  the  mile.  Later,  one  at  3  inches  to  the 
mile  for  practice  in  road  sketching  should  be  made,  and  when 
mounted  work  is  taken  up,  a  scale  reading  minutes  and  fractions 
of  minutes  of  travel  of  the  horse  at  trot  and  walk  at  3  inches 
to  the  mile  will  be  needed. 

The  making  of  a  scale  for  working  purposes  is  simple  and 
easy  enough  if  it  be  kept  clearly  in  mind  that  it  is  merely  a  de- 
termination of  the  length  that  will  be  required  to  show  a  given 
number  (usually  100)  of  strides  on  the  ground  at  the  scale 
desired. 

To  make  a  working  scale  of  strides  at  6  inches  to  the  mile, 
measure  off  with  chain  or  tape  a  ground  course  along  a  road  or 
preferably  across  country  "  over  hill  and  dale  "  of  1  mile,  three- 
quarters  of  a  mile,  or  one-half  of  a  mile.  The  longer  the  course 
the  better.  It  should  be  over  average  ground  (up  and  down  hill) 
similar  to  that  which  is  to  be  sketched  and  should  be  carefully 
measured. 

Walk  this  course  both  ways  several  times,  counting  strides 
with  the  tally  register  as  described  under  "  Tally  Register,"  or 
by  counting  and  tallying  every  100  strides  with  paper  and  pencil. 
Do  this  on  different  days  and  at  different  times  of  day. 

When  it  is  found  that  the  number  of  strides  required  to  trav- 
erse the  distance  is  fairly  uniform,  take  the  average  of  the 
last  half  dozen  trials  to  determine  your  average  for  that  distance. 

In  any  method  of  constructing  a  scale  the  above  steps  must  be 
taken.  The  further  proceedings  in  the  actual  laying  off  and 
marking  off  the  scale  may  be  accomplished  in  several  ways. 
Two  ways  considered  the  simplest  and  easiest  are  given  here. 

The  first  method  is  to  lay  off  on  your  paper  the  scale  distance 
in  inches  of  the  course  and  divide  it  into  as  many  parts  and 
fractional  parts  as  you  have  hundreds  and  fractions  of  hundreds 
of  strides  in  your  average. 


30  SKETCHING  METHODS. 

Each  full  division  will  then  show  the  length  on  the  working 
scale  that  will  represent  100  of  your  strides  at  the  desired  scale. 
The  fractional  division  will  represent  an  odd  number  of  strides 
and  may  be  erased,  as  there  is  no  need  for  it. 

As  an  example,  assume  that  you  find  the  average  number  of 
strides  to  cover  a  measured  1-mile  course  is  1,048.  Lay  off  a 
Hue  6  inches  in  length  (the  scale  distance  for  1  mile)  and  divide 
it  into  10.48  equal  parts. 

Each  full  division  will  show  the  distance  on  your  working 
scale  which  is  required  to  represent  100  of  your  strides  at  a 
scale  of  6  inches  to  the  mile. 

To  complete  your  scale,  divide  the  left  one  of  the  100  stride 
divisions  into  10  equal  parts.  This  part  of  the  scale  is  called 
the  extension  and  is  made  in  this  way  for  convenience.  Each 
of  the  10  parts  in  the  extension  represents  10  of  your  strides. 
Mark  the  dividing  line  between  the  extension  and  the  main 
scale  as  zero  and  then  each  dividing  line  along  the  main  scale 
between  the  other  parts  with  the  number  of  hundreds  of  strides 
it  measures  from  the  zero  mark. 

It  should  be  remembered  that  when  this  method  is  used  the 
line  to  be  divided  in  making  a  scale  corresponding  to  6  inches 
to  the  mile  must  be  the  same  proportional  part  of  6  inches  that 
the  course  on  which  the  average  number  of  strides  was  se- 
cured is  of  1  mile.  That  is,  if  the  course  is  1  mile,  lay  off  6 
inches;  if  it  is  three-fourths  of  a  mile,  lay  off  (three-fourths  of 
6  inches)  4£  inches;  and  if  the  course  is  one-half  mile,  lay  off 
(one-half  of  6  inches)  3  inches. 

The  second  method  is  to  ascertain  the  length  in  inches  or 
fractions  of  an  inch  which  will  represent  100  of  your  strides. 
Having  this,  lay  off  the  number  of  divisions  of  that  length  de- 
sired, mark  them  and  paste  them  on  the  ruler.  For  example: 
Assume  that  the  average  number  of  strides  to  1  mile  is  1,048. 
It  is  desired  to  construct  a  working  scale  at  6  inches  to  1  mile. 
Divide  6  by  10.48  and  the  result  (0.572  inch)  will  be  the  length 
on  your  working  scale  which  will  represent  100  of  your  strides 
at  6  inches  to  1  mile. 

With  a  scale  of  equal  parts  (one  reading  inches  and  tenths 
of  inches  will  serve),  lay  off  as  many  divisions  0.572  inch  long 
as  you  may  desire  in  your  scale,  and  each  of  them  will  repre- 
sent 100  of  your  strides  at  6  inches  to  the  mile.  Mark  off  the 
extension  and  the  main  scale  as  previously  described,  trim  to 
suit,  and  paste  on  ruler. 


SKETCHING  METHODS.  31 

When  a  scale  of  strides  for  6  inches  to  the  mile  has  been 
made,  all  that  is  necessary  to  construct  one  at  3  inches  to  the 
mile  is  to  take  off  on  a  piece  of  paper  the  divisions  on  the  6-inch 
scale  and  mark  them  with  just  twice  the  value  they  have  at 
the  6-inch  scale.  Each  division  of  the  extension  will  represent 
20  strides  at  3  inches  to  the  mile. 

Either  of  the  foregoing  methods  may  be  used  in  constructing 
a  time  scale  for  a  horse.  It  is  first  necessary  that  the  horse 
should  be  trotted  and  walked  several  times  over  a  course  and 
his  average  time  of  travel  secured.  In  doing  this  care  should 
be  exercised  that  the  horse's  gait  is  not  influenced  by  the  pres- 
ence of  another  horse,  the  fact  that  the  animal  is  tired  or 
fresh,  that  he  is  going  toward  or  away  from  the  stable,  etc. 
Allowances  must  be  made  for  such  things,  and  practice  enough 
should  be  had,  before  constructing  the  scale,  to  enable  the 
sketcher  to  determine  pretty  well  whether  or  not  the  horse  is 
taking  a  uniform  gait. 

Working  scales  should  be  tested  from  time  to  time  by  the 
sketcher  in  order  to  be  sure  that  his  stride  is  not  changing. 
This  can  be  done  by  occasionally  checking  traverses  with  a 
Geological  Survey  map  or  by  measuring  with  chain  and  tape 
some  of  the  distances  traversed. 

WHAT  A  SKETCH  SHOULD  SHOW. 

Broadly  speaking,  a  military  sketch  should  show  all  natural 
and  artificial  features  of  the  surface  of  the  earth  in  the  area 
sketched.  The  magnetic-meridian  line,  a  title  giving  the  char- 
acter of  the  sketch,  the  locality  sketched,  the  date,  the 
sketcher's  name,  the  scale  of  the  sketch,  and  a  graphic  scale 
reading  hundreds  of  yards  should  also  be  shown. 

Natural  features  (bodies  of  water,  woods,  etc.)  and  all  "  works 
of  man "  are  represented  by  conventional  signs,  drawings  to 
scale,  or  by  written  words. 

The  configuration  of  the  ground  is  represented  by  contours 
showing  elevations  and  depressions  with  the  character  of  their 
slopes  and  relative  heights  as  truly  as  the  scale  of  the  sketch, 
the  time  allowed,  and  the  sketcher's  ability  will  permit. 

All  detail,  except  that  shown  by  contours,  is  called  flat  or 
horizontal  detail.  That  shown  by  contours  is  called  vertical 
detail.  The  military  sketch  must  have  every  feature  located 
in  its  relative  horizontal  and  vertical  position. 


32  SKETCHING  METHODS. 

HORIZONTAL  DETAIL. 

The  horizontal  position  of  any  point  is  determined  when  its 
direction  and  distance  from  a  previously  determined  point  are 
shown.  The  vertical  position  is  determined  when  its  elevation 
with  reference  to  an  assumed  level,  called  a  datum  plane,  is 
shown. 

The  line  from  which  all  directions  are  measurd  is  the  plane 
of  the  magnetic  compass  needle,  called  the  magnetic  meridian. 
The  true  north  and  south  line  (true  meridian)  need  not  be  con- 
sidered in  sketching.  It  is  most  important  when  direction  lines 
from  one  point  to  another  are  located  that  the  sketching  board 
be  oriented  (explained  under  "Sketching  Board").  The 
sketcher  should  therefore  always  verify  the  position  of  the 
needle  or  of  the  arrow  on  his  board  before  drawing  a  ray  (light 
line)  toward  the  object  whose  direction  is  being  determined. 

The  position  of  a  point,  with  reference  to  direction  and  dis- 
tance, is  determined  in 'one  of  the  following  ways :  (1)  Travers- 
ing; (2)  intersection;  (3)  resection;  (4)  estimation. 

TRAVERSING. 

By  this  is  meant  the  measurement  of  the  distance  between 
two  points  by  counting  the  strides  or  time  of  travel  required  to 
pass  from  one  to  the  other. 

The  term  traverse  is  applied  to  the  route  followed  by  the 
sketcher  in  making  the  sketch. 

To  locate  a  point  by  traversing. — Being  at  point  A  (whose 
position  is  plotted  on  your  sketch)  with  the  board  oriented, 
stick  a  pin  in  point  A,  on  the  sketch.  Lay  ruler  alongside  the 
pin  and  pivot  it  around  until  point  B  (the  point  to  which  you 
are  to  traverse)  is  sighted.  Verify  the  position  of  the  arrow 
and  then  draw  a  ray  toward  B.  Move  to  B,  counting  strides, 
and  upon  arrival  lay  your  ruler  along  the  ray  with  the  zero 
of  scale  of  strides  at  A  and  lay  off  on  the  ray  the  number  of 
strides  that  you  took  between  the  two  points.  The  point 
marked  is  B. 

INTERSECTION. 

The  position  of  a  point  is  determined  in  this  method  by  draw- 
ing rays  toward  it  from  each  of  two  other  points,  whose  posi- 
tions are  already  determined  and  plotted  on  the  sketch.  Tho 
intersection  of  the  two  rays  is  the  sketch  position  of  the  point 
sighted. 


SKETCHING  METHODS.  33 

To  locate  the  position  of  a  point  by  intersection. — Assume 
that  from  point  A,  with  your  board  oriented,  you  took  a  careful 
sight  and  drew  a  ray  toward  a  church  a  few  hundred  yards  off 
to  the  side.  After  arriving  at  B  and  plotting  its  position,  you 
carefully  orient  the  board  by  a  back  sight  on  A.  Pivot  the  ruler 
around  the  pin  in  B  until  the  church  is  sighted,  then  draw  a  ray 
toward  the  church.  The  intersection  of  this  ray  with  the  one 
you  drew  from  A  is  the  sketch  position  of  the  church. 

RESECTION. 

This  is  determining  the  sketcher's  position  by  orienting  the 
board  and  drawing  rays  toward  himself  from  two  or  more 
points  whose  positions  are  already  determined  and  plotted. 

To  locate  position  by  resection. — After  having  plotted  the  po- 
sition of  points  A  and  B,  the  sketcher  comes,  into  his  area  later 
at  some  point  from  which  those  two  points  can  be  seen.  His 
present  position  is  not  yet  determined.  To  determine  it,  set  up 
the  board  and  orient  as  carefully  as  possible  by  the  arrow,  then 
stick  pins  in  the  sketch  positions  of  points  A  and  B..  Pivot  the 
ruler  around  the  pin  at  A  on  the  sketch  until  you  sight  A  on  the 
ground  and  after  verifying  the  position  of  the  arrow,  draw  a 
ray  toward  yourself.  Next  pivot  the  ruler  around  the  pin  at  B 
on  the  sketch  until  you  sight  B  on  the  ground,  and  after  glanc- 
ing at  arrow,  draw  a  ray  from  that  point  toward  yourself.  The 
intersection  of  the  two  rays  is  the  sketcher's  position. 

There  are  other  methods  of  resection,  but  their  use  is  so  ex- 
ceptional that  they  need  not  be  considered. 

ESTIMATION. 

After  some  practice,  points  nearby  are  located  very  accurately 
by  simply  estimating  their  distance  and  plotting  their  position 
on  a  ray  drawn  toward  them.  Advantage  is  taken  of  any  fea- 
ture in  the  locality  that  may  assist  in  determining  the  distance, 
such  as  telegraph  or  telephone  poles,  fence  posts,  section  lines, 
etc.  The  ability  to  estimate  distances  should  be  cultivated  at 
every  opportunity.  A  good  sketcher  must  be  able  to  estimate 
with  less  than  10  per  cent  error  up  to  about  300  yards  and 
within  20  per  cent  up  to  a  mile.  This  ability  can  only  be  ac- 
quired by  constant  practice  and  by  verifying  the  estimates  by 
measurements.  All  estimates  should  be  made  in  yards,  and  100 
yards  should  be  definitely  fixed  in  mind  as  a  reference  unit. 

Do  not  estimate  on  main  traverse. 


34  SKETCHING  METHODS. 

VERTICAL  DETAIL. 

The  United  States  Geological  Survey  uses  sea  level  as  datum 
plane  in  determining  elevations  of  points. 

In  military  sketches  the  area  is  comparatively  so  small  that 
the  datum  plane  used  is  immaterial.  The  reason  for  this  is 
that  what  is  desired  is  the  elevation  of  the  different  points  in 
the  area  with  relation  only  to  the  other  points  in  it.  It  is  im- 
material whether  the  elevation  of  the  starting  point  is  assumed 
to  be  500  feet  or  1,000  feet,  but  all  other  points  must  then  show 
their  elevation  with  reference  to  the  assumed  one. 

It  is  well  to  ascertain  the  Geological  Survey  elevation  of 
some  point  and  start  from  there,  because  the  sketch  can  be 
checked  against  a  Geological  Survey  map  more  conveniently 
when  the  elevations  are  the  same,  but  it  is  not  at  all  necessary 
that  this  be  done. 

Under  our  normal  system  of  scales  the  vertical  interval 
(V.  I.)  used  on  military  maps  and  sketches  can  be  found  by 
dividing  the  number  of  inches  representing  1  mile  in  the  scale 
into  60.  For  example,  at  6  inches  to  1  mile  the  V.  I.  is  10  feet. 
At  3  inches  it  is  20  feet,  and  at  12  inches  to  1  mile  the  V.  I.  is 
5  feet. 

The  vertical  position  of  a  point  is  located  by  determining  its 
elevation  above  or  below  some  other  point  whose  elevation  has 
already  been  determined. 

The  determining  of  difference  of  elevation  of  two  points  by 
estimation  is  the  method  of  the  experienced  and  rapid  sketcher. 
After  some  time  and  with  considerable  practice  the  sketcher 
acquires  ability  to  estimate  differences  with  great  accuracy. 

There  are  many  ways  in  which  practice  in  estimating  eleva- 
tions may  be  had.  The  ability  to  strike  one's  own  level  is  of 
great  value.  This  can  be  practiced  indoors  by  swinging  the 
extended  arm  around  with  the  hand  at  level  of  the  eye,  so 
that  the  line  of  sight  over  the  back  of  the  hand  passes  through 
marks  made  upon  the  wall  at  the  exact  height  of  the  eye. 

Having  learned  to  strike  your  own  level,  practice  estimating 
distances  or  objects  above  and  below  this  plane  by  comparison 
with  the  heights  of  ordinary  objects  in  the  vicinity,  such  as 
telegraph  poles,  trees,  etc.  Fix  in  mind  a  10-foot  unit  and  apply 
this  to  the  height  being  determined. 

In  connection  with  estimating  either  horizontal  or  vertical 
distances  it  is  well  for  the  beginner  to  remember  that  it  is 


SKETCHING  METHODS.  35 

fatal  to  good  estimation  to  depend  upon  his  judgment  until  he 
has  a  definite  and  clear  idea  of  what  the  units  of  measure  he 
is  using  really  are,  and  hence  he  should  if  possible  check  all 
estimates  until  he  has  attained  the  ability  to  estimate  with  a 
minimum  of  error.  This  will  come  only  with  practice  and  con- 
stant checking. 

CONTOURS. 

The  representation  of  vertical  distances  by  means  of  corf- 
tours  seems  hard  to  the  beginner.  This  is  largely  due  to  the 
fact  that  the  average  beginner  usually  attempts  to  contour  be- 
fore he  really  knows  what  a  contour  is,  what  laws  govern  their 
making,  or  what  may  be  shown  by  them  at  the  scale  being  used. 
Before  attempting  to  do  any  contouring  in  the  field  the  begin- 
ner should  gain  a  clear  idea  of  these  things  by  careful  study 
and  much  practice,  so  that  when  he  takes  up  contouring  he  will 
know  what  he  is  trying  to  do. 

Contours  are  lines  drawn  on  a  map  or  sketch,  which,  follow- 
ing the  various  levels  at  fixed  vertical  intervals,  indicate  the 
shape  of  the  ground  and  show  its  vertical  irregularities. 

The  general  laws  governing  the  use  of  contours  may  be  fully 
learned  only  by  actual  field  work.  Some  are  noted  here: 

1.  Every  contour  line  either  closes  on  itself  or  both  ends  of 
it  go  off  the  sketch. 

2.  Every  part  of  a  contour  line  is  at  the  same  level. 

3.  A  contour  about  to  cross  a  stream  line  runs  up  on  one  side 
of  the  stream  and  comes  down  on  the  other,  making  a  V  where 
it  crosses.    The  apex  of  the  V  points  upstream. 

4.  Contours  representing  spurs  between  stream  lines  are  gen- 
erally  U-shaped,  with  the  bottom  or  rounded  part  of  the   U 
pointing  clown  hill. 

5.  Valley  contours  apparently  go  in  pairs ;  that  is,  the  contour 
next  to  the  stream  line  on  one  side  is  the  same  contour  as  the 
one  next  to  the  stream  line  on  the  opposite  side.     If  you  cross 
the  800-foot  ?evel  just  before  you  wade  into  a  stream,  you  must 
cross  that  same  level  again  when  you  wade  out  on  the  opposite 
side. 

6.  Ridge  contours  also  apparently  go  in  pairs.     The  contour 
next  to  the  top  of  a  ridge  has  its  mate  next  to  it  just  over  the 
ridge. 

7.  In  the  case  of  the  contours  on  opposite  sides  of  the  stream 
their  meeting  point  will  generally  be  found  close  by ;  in  those 


36  SKETCHING  METHODS. 

next  to  the  ridge  top  it  may  be  that  they  do  not  join  up  on  the 
sketch,  but  if  the  area  were  extended  their  meeting  point  would 
be  found  sooner  or  later. 

In  sketching  do  not  attempt  to  show  a  cliff  by  contours. 
Break  the  contour  lines  on  each  side  and  write  "Cliff  60'  "  (or 
whatever  its  height  may  be).  Do  the  same  with  a  bluff  which  is 
so  high  and  steep  as  to  make  difficult  clear  representation  by 
means  of  contours.  If  you  have  a  depression  to  represent,  be 
sure  that  the  contours  showing  it  are  clearly  numbered,  so  that 
it  may  at  once  be  understood. 

DETAIL  SHOWN  BY  CONTOURS. 

The  amount  of  detail  that  may  be  shown  by  contours  depends 
directly  upon  the  scale  of  the  sketch.  Failure  to  realize  this  is 
one  of  the  reasons  why  the  representation  of  ground  forms  by 
contours  is  often  difficult  for  the  beginner.  For  example,  on  a 
scale  of  3  inches  to  the  mile  a  spur  100  feet  long  jutting  out 
from  a  hillside  would  cause  a  contour  line  to  change  about  one- 
twentieth  inch,  the  scale  width  of  the  spur.  If  trouble  were 
taken  to  change  an  otherwise  regular  contour  to  indicate  this 
no  one  would  notice  it  nor  care  anything  about  it  if  it  were 
noticed.  It  is  true  that  this  spur  might  furnish  cover  to  a  num- 
ber of  the  enemy,  but  when  the  commander  wants  a  sketch  in 
which  such  cover  becomes  important,  he  will  have  it  made  on  a 
larger  scale. 

The  minimum  size  of  ground  features  that  can  be  shown  to 
advantage  to  the  scale  used  should  be  determined  and  kept 
clearly  in  mind  by  the  sketcher.  Then,  so  far  as  anything 
smaller  is  concerned,  he  should  regard  the  ground  as  smooth 
and  regular.  This  will  greatly  simplify  his  work. 

It  must  be  realized  that  any  details  that  can  not  be  shown 
dearly  and  naturally  to  the  scale  ordered  are  not  wanted. 
This,  of  course,  refers  only  to  those  features  that  are  to  be 
shown  to  scale.  Houses,  bridges,  roads,  stream  lines,  etc.,  being 
represented  by  conventional  signs  are  not  drawn  to  scale. 

A  good  method  to  follow  to  gain  an  idea  of  what  can  be  shown 
at  the  various  scales  by  contours  is  to  take  a  map  or  sketch  of 
an  area  and  carefully  study  the  ground  represented  and  note 
the  smaller  details  that  are  not  'shown  on  the  map.  Compare 
map  and  ground,  again  noting  carefully  the  ground  forms  as 
they  are  on  the  ground  and  then  how  they  are  represented  on 
the  map. 


SKETCHING  METHODS.  37 

A  box  filled  with  sand,  called  a  sand  table,  is  a  great  aid  in 
studying  ground  forms  and  may  be  used  if  time  permits  and 
outdoor  work  can  not  be  done.  Many  exercises  can  be  held  in 
which  much  can  be  accomplished  in  learning  how  to  contour. 
Make  a  mound,  assume  a  scale,  and  represent  it  by  contours. 
After  drawing  in  the  flat  detail  of  a  sand-table  terrain,  contour 
the  area,  first  determining  the  elevation  of  the  critical  points, 
then  spacing  the  contour  points  by  eye,  according  to  the  slopes, 
and  then  connecting  up  the  levels. 

Take  a  section  of  a  contoured  map  and  reproduce  it  on  the 
sand  table  according  to  scale.  Later,  without  looking  at  the  con- 
toured map,  make  a  sketch  of  the  area  and  compare  it  with  the 
contoured  map. 

Any  ground  forms  can  be  produced  and  their  contour  lines 
studied  out  and  drawn.  The  amount  of  work  that  can  be  done 
on  the  sand  table  depends  upon  the  time  the  student  will  give 
to  it  and  his  ingenuity. 

The  value  of  the  sand  table  is,  of  course,  limited  to  giving 
a  thorough  understanding  of  ground  forms  and  of  their  repre- 
sentation by  contour  lines.  This  understanding  is  essential  to 
the  sketcher.  Practical  familiarity  with  ground  forms  and 
ability  to  represent  them  correctly  can  only  be  gained  on  the 
ground,  for  the  only  way  in  which  the  ground  perspective  can 
be  appreciated  is  by  study  of  the  ground  itself.  To  the  be- 
ginner, ground  distances  appear  greater  and  features  near  by 
larger  than  they  actually  are,  and  this  can  only  be  corrected  by 
actual  work  on  the  ground. 

LOGICAL  CONTOURING. 

The  Engineer  Department  at  the  Army  Service  Schools  at 
Fort  Leavenworth  has  had  printed  a  number  of  plates  fqr  the 
purpose  of  practice  in  drawing  contours.  These  show  the  flat 
details  of  the  area  and  the  elevations  of  critical  points.  The 
entire  series  should  be  filled  in  by  every  beginner  and  corrected 
by  an  instructor  before  attempting  any  fieldwork  other  than 
fillin"  in  flat  details.  The  series  consists  of  several  sheets,  each 
with  four  areas.  These  can  be  secured  at  small  cost  from  the 
Book  Department,  Army  Service  Schools.  Too  much  of  this 
practice  can  not  be  had.  The  method  of  filling  in  the  contours 
is  illustrated  in  figures  8,  9,  10,  and  11. 


38 


SKETCHING  METHODS. 


Practice  in  logical  contouring,  as  it  is  called,  is  most  neces- 
sary to  a  clear  understanding  of  contouring  in  sketching.    The 


Arrow  heads  on  Fig.  8  show  direction  of  water  flow. 
Place  10'  contours  on  the  above  sketch. 


667  850 


*g?o 


663 


Arrow  points  on  Fig.  9    (except  those  also  appearing  on  Fig.  8)   are 
points  where  contours  cross  streams  or   dry  runs. 

more  of  it  a  student  does  the  better.  Anyone  can  make  up  a 
framework,  similar  to  those  shown  in  figures  8,  12,  and  13,  and 
practice  contouring  by  logical  methods. 


SKETCHING  METHODS. 


39 


The  procedure,  as  shown,  is  to  first  note  the  elevations  of 
critical  points  along  stream  lines  and  ridges,  then  divide  up  and 
mark  crossing  points  of  contour  lines  along  the  main  stream 


Fig.  10 


line,  then  along  the  tributary  streams,  marking  those  on  stream 
lines  with  a  V  pointing  upstream,  then  from  points  along  the 


stream  lines  to  ridge-line  points  near  by,  mark  (with  dots  or 
short  lines)  the  crossing  points  of  the  number  of  contour  lines 
that  go  between,  according  to  the  elevations  of  the  top  and  bot- 


40  SKETCHING  METHODS. 

torn   points.     Finally,   having   enough   of   these   to   shape   the 
ground,  join  them  up  by  long  curving  lines. 

On  all  sketches,  the  contour  lines  should  be  numbered  so 
that  the  elevation  of  any  one  of  them  can  be  readily  found. 
They  should  be  numbered  where  they  leave  the  area  and  occa- 
sionally along  a  stream  line  or  on  some  of  the  longer  slopes 
(fig.  11).  The  completed  sketch  should  have  each  50  or  100 
foot  contour  line  drawn  heavier  than  the  others. 

CONTOUR  FRAMEWORK. 

Critical  points  are  those  at  which  an  abrupt  change  in  direc- 
tion or  slope  takes  place,  such  as  bends  in  roads  or  streams, 
stream  junctions,  tops  of  ridges,  hills,  etc.  Any  feature  which 
may  assist  the  sketcher  in  securing  his  framework,  may  be 
called  a  critical  point. 

Manifestly,  it  is  impracticable  to  determine  the  exact  location 
of  the  crossing  points  of  each  contour  line  between  all  the  criti- 
cal points.  It  is  equally  impracticable  to  determine  the  location 
of  every  slight  change  of  slope  on  a  hillside.  Such  detail  is  not 
important  and  is  not  wanted.  Hence,  the  sketcher  ascertains 
the  elevation  of  critical  points,  thus  locating  the  position  of 
the  form-controlling  contours  and  interpolates  the  contour  lines 
between  them,  spacing  by  eye  to  indicate  the  change  of  slope  as 
these  changes  appear  to  him. 

The  undulations  and  vertical  distances  in  the  form  of  the 
ground  are  largely  caused  by  the  erosive  action  of  rainfall, 
hence  the  drainage  system  and  ridge  lines  form  the  framework 
on  which  contours  are  hung. 

If  the  sketcher  determines:  (1)  The  elevation  of  the  main 
stream  line  at  the  point  where  it  enters  his  area ;  (2)  the  eleva- 
tion of  its  junction  with  its  tributaries,  in  the  area;  (3)  the 
elevation  of  the  main  stream  where  it  leaves  the  area,  he  will 
have  a  good  base  from  which  to  build  up  his  contours.  If,  while 
determining  the  above,  he  also  determines  the  elevations  of  the 
tops  of  the  ridge  lines  between  the  stream  branches  and  of  im- 
portant points  along  and  on  these  ridges,  he  will  have  the  high- 
est as  well  as  the  lowest  levels  in  the  area  and  need  only  fill  in 
the  contours  between  the  points  whose  elevations  are  known. 

The  foregoing  is  exactly  what  the  sketcher  must  do  in  con- 
touring. As  he  goes  over  his  area,  drawing  to  scale  the  flat  or 
horizontal  details,  he  locates  all  critical  points  and  estimates 
and  notes  their  elevation.  Then,  having  enough  of  the  drainage 


SKETCHING  METHODS.  41 

system  and  ridge  lines  "  pinned  down  "  to  enable  him  to  show 
the  big  features,  he  dots  in  the  level  lines  at  their  proper  vertical 
intervals  between  critical  points  according  to  the  slope  of  the 
ground.  Finally  he  connects  up  the  dotted  points  by  contour 
lines,  each  running  through  the  dots  of  its  own  elevation. 

In  reality,  contour  lines  in  sketching  are  nothing  more  than 
conventional  signs.  A  sketcher  will  soon  find  that  every  slope  is 
one  of  three  kinds — uniform,  concave,  or  convex.  When  spac- 
ing in  contours,  this  should  be  kept  in  mind.  Any  slope  of 


F,g/<L 


V 

terookrfe  10'Contoury 


ground  may  be  divided  into  sections,  each  of  which  may  be  repre- 
sented by  one  of  the  three  kinds  mentioned.  Practice  alone  will 
enable  one  to  pick  out  the  dividing  lines,  but  they  should  be 
looked  for  from  the  beginning. 

Where  the  slope  is  uniform,  space  your  contours  equal  dis- 
tances apart ;  where  the  slope  is  concave  in  form,  space  your  con- 
tour lines  closer  together  near  the  higher  elevation  and  wider 
apart  toward  the  lower ;  where  the  slope  Is  convex,  space  them 
wider  at  the  higher  and  closer  at  the  lower  elevation. 


42 


SKETCHING  METHODS. 


The  beginner  must  learn  to  consider  general  knowledge  of 
country,  of  rates  of  fall  of  streams,  of  railroad  grades,  and  of 
ground  forms  in  order  to  keep  his  work  logical  and  consistent. 
For  instance,  large  rivers  have  a  fall  of  only  a  few  inches  to  the 
mile,  unless  there  are  many  rapids  ;  therefore,  within  the  limits 
of  an  ordinary  reconnaissance  sketch,  a  large  river  is  at  the 
same  level,  for  purposes  of  determining  elevations.  A  stream 


IQOOtl 


r-  I  a  tnttrpo/ote  IO' Contours 


line  carrying  water  all  the  year  round  has  a  less  fall  per  mile 
than  one  in  the  same  area  which  is  dry  part  of  the  time.  Tribu- 
tary streams  have  a  greater  fall  than  main  stream  lines.  The 
nearer  the  stream  to  the  source,  the  steeper  it  falls. 

NOTES  FOR  FIELD  WORK. 

Avoid  complicated  and  Cumbersome  methods. 
Always  use  the  simplest  and  most  common-sense  way. 
Do    everything    possible,    consistent    with    requirements    of 
making  the  sketch,  to  save  time.    When  you  halt  to  make  a  note, 


SKETCHING  METHODS.  43 

make  it,  and  go  on.  When  you  halt  to  fill  in  something  and  it 
is  not  necessary  to  orient,  do  not  orient  but  do  the  filling  in 
quickly,  and  move  on. 

Never  orient  the  board  unless  there  is  necessity  for  it. 

Every  time  you  orient  the  board  by  arrow  or  compass,  verify 
it  by  a  back  sight,  if  practicable.  Every  time  you  orient  by  a 
Jback  sight,  verify  it  by  the  arrow  or  compass. 

Always  verify  the  orientation  just  before  you  draw  a  ray 
either  along  a  traverse  or  in  intersection  or  resection. 

Try  to  acquire  the  habit  of  doing  the  necessary  things  at 
each  halt  in  the  same  sequence.  For  example,  traversing  along 
a  road,  you  arrive  at  the  top  of  a  rise,  to  which  you  had  drawn 
a  ray.  Halt  there,  look  around,  and  select  the  best  position 
for  sighting  forward  on  the  traverse.  Lay  the  board  down  on 
the  ground  or  place  it  on  your  knees.  Take  out  ruler  and  pencil, 
and  placing  ruler  alongside  the  ray,  with  edge  of  working  scale 
next  to  it,  measure  off  the  number  of  strides  from  last  station 
and  mark  with  pencil  dot.  Stick  a  pin  in  this  dot  which  is 
your  present  station.  Lay  ruler  along  ray  to  last  station  and 
orient  board  by  back  sight.  Having  the  board  oriented, 
pivot  the  ruler  around  the  pin  and  draw  a  ray  to  the  next 
station.  Now  sight  and  draw  rays  to  such  points  as  you 
may  have  drawn  rays  to  from  previous  station,  to  complete  their 
location  by  intersection  and  then  draw  rays  to  such  new  points 
as  in  your  judgment  may  be  of  use,  noting  in  each  case  the 
object  sighted.  Verify  orientation  each  time  before  drawing 
ray.  Now  draw  in  the  other  road  line  (the  ray  taken  to  this 
station  is  one)  and  fill  in  the  flat  details,  houses,  bridges,  stream 
lines,  fence  signs,  etc.,  from  the  last  station  to  your  present  one. 
Determine  the  elevation  of  your  present  station  by  estimating 
the  difference  between  it  and  the  previous  one.  In  the  same 
manner  determine  the  elevation  of  any  critical  points  that  you 
may  have  noted  in  your  traverse  from  last  station  as  well  as 
of  points  located  by  intersection.  If  you  have  enough  data  to 
enable  you  to  contour  between  stations,  do  it  now;  if  not,  be 
sure  that  the  elevations  of  critical  points  are  noted.  Put  the 
ruler,  pencil,  eraser,  pin,  etc.,  in  their  proper  places,  pick  up 
the  board,  and  start  traverse  to  next  station. 

The  operations  noted  in  the  foregoing  have  to  be  carried  out 
at  each  station.  Failure  to  carry  them  out  in  sequence  while 
learning  to  sketch  will  handicap  the  beginner  very  much.  It 


44  SKETCHING  METHODS. 

is  therefore  considered  essential  that  the  beginner  should  learn 
to  do  them  in  the  sequence  described.  After  a  while  he  will  de- 
velop the  simplest  and  best  way  for  himself.' 

Have  your  sketch  completed  up  to  your  station  before  moving 
on.  In  the  earlier  stages  this  applies  only  to  flat  details,  later 
to  both  horizontal  and  vertical  detail  in  road  sketching  and 
to  horizontal  detail  and  the  location  and  determination  of  the 
elevation  of  critical  points  in  making  a  position  sketch.  The 
contouring  in  this  case  is  not  undertaken  until  the  entire  frame- 
work of  ridge  and  stream  lines  is  "  pinned  down." 

Be  particular  that  the  information  conveyed  is  not  misleading. 
It  is  better  to  leave  a  part  blank  than  to  deceive  or  mislead. 

Try  to  put  equal  care  and  time  on  all  parts  of  the  sketch. 
Avoid  excessive  care  at  the  beginning  followed  by  excessive  haste 
near  the  end. 

Acquire  method  and  system  in  your  sketching  and  the  rest 
will  be  easy. 

POSITION  SKETCH. 

It  is  assumed  that  before  undertaking  to  make  a  position 
sketch  the  sketcher  has  followed  out  the  course  of  study  outlined 
herein. 

Select  an  area  of  ground  about  one-half  a  mile  square.  One 
having  roads  on  all  sides  is  better,  but  this  is  not  material. 

Determine  where  to  locate  your  starting  point  on  the  paper 
by  estimating  the  direction  from  you  in  which  the  area  to  be 
sketched  lies.  If  you  are  at  the  southwest  corner  of  the  area, 
locate  your  starting  point  (by  sticking  in  a  pin)  about  5  inches 
from  the  west  edge  and  5  inches  from  the  south  edge  of  the 
paper.  Since  the  area  to  be  sketched  will  occupy  about  3  inches 
square  when  drawn  to  scale,  you  will  thus  have  it  at  about  the 
center  of  the  sheet. 

Draw  the  magnetic  meridian  line  parallel  to  the  edge  of  the 
paper,  then  orient  board.  Take  forward  sight  to  next  station 
and  draw  ray  toward  it.  Assume  elevation  of  starting  point 
and  note  it.  Now  traverse  all  the  way  around  the  area,  locating 
as  you  go  the  position  and  elevation  of  all  critical  points  along 
the  traverse.  Fill  in  all  horizontal  detail  along  and  near  the 
traverse,  inside  the  area,  within  easy  estimating  distance  (a 
couple  of  hundred  yards)  by  estimation  and  farther  off  by  inter- 
section methods. 


SKETCHING  METHODS.  4o 

In  traversing  around  the  area,  in  addition  to  cuts,  fills, 
orchards,  etc.,  locate  the  following : 

1.  Every  stream  or  drainage  line  crossing  the  traverse  or 
running  close  to  it.    Note  the  direction  of  its  flow  and  its  fall.    If 
this  is  not  at  once  apparent,  take  time  to  find  out.     This  is 
important. 

2.  Every  house  or  other  feature  easily  identified  near  the 
traverse,  which  may  later  be  useful  in  finding  yourself.    Some- 
times some  feature  outside  of  the  area  may  be  extremely  valu- 
able.   For  example,  a  tall  chimney  some  hundreds  of  yards  from 
the  area  may  be  visible  from  all  points  in  it ;  to  locate  this  by 
intersection  early  in  the  work  may  save  much  time  later. 

3.  The  high  points  between  drainage  lines  along  the  traverse 
(determine  and  note  their  elevations).     Proceeding  simultane- 
ously with  the  traversing,  dot  in  (according  to  the  slope  of  the 
ground)  and  mark  the  crossing  points  of  the  contours  between 
critical  points  along  the  traverse  whose  elevations  have  been 
determined.     Do  not  draw  any  contours  yet;  wait  until  later, 
when  you  have  the  stream  line  and  ridge  framework  completed 
and  can  see  the  area  as  a  whole.    The  big  features  will  then  be 
distinct,  and  the  little  ones  will  take  care  of  themselves. 

ADJUSTMENT  TO  CLOSE. 

When  you  reach  a  point  from  which  the  starting  point  can  be 
seen,  you  will  probably  find  that  the  ray  to  that  point  does  not 
pass  directly  through  it.  This  is  to  be  expected.  If  the  error 
is  less  than  10  per  cent  of  the  entire  length  of  the  traverse,  it  is 
satisfactory.  If  it  is  greater,  there  has  probably  been  some 
error  in  your  orientation.  If  you  are  not  able  to  determine 
just  where  the  mistake  occurred,  distribute  the  error  by  ad- 
justment. To  do  this,  move  the  last  point  to  or  from  the  point  of 
starting,  the  next  traverse  line  a  little  less  in  the  same  direc- 
tion, and  the  next  one  a  little  less  than  the  previous  one.  Re- 
member the  scale  you  are  using  and  the  scale  width  of  a  road 
as  it  is  drawn  on  the  sketch.  Do  not  waste  time  in  making  this 
adjustment,  but  in  making  it,  be  sure  that  you  do  not  make  an 
angle  between  roads  which  is  noticeably  different  from  the 
actual  ground  angle  made  by  the  roads.  Otherwise  some  one 
may  be  misled.  Tour  sketch  will  have  errors  in  it,  but  it  must 
not  contain  misleading  or  deceptive  information. 


46  SKETCHING  METHODS. 

COMPLETING  SKETCH. 

Having  traversed  completely  around  your,  area  and  having 
noted  the  location  of  all  drainage  lines  crossing  its  borders,  you 
will  have  a  pretty  fair  idea  as  to  which  is  the  main  stream  line 
and  where  it  lies.  You  must  now  find  out  how  the  smaller 
stream  lines  connect  up  with  it  in  the  area  in  order  to  com- 
plete your  framework.  It  is  now  time  to  traverse  into  the 
interior.  Select  a  road  or  trail  if  one  is  nearby ;  if  not,  select 
some  point  in  the  interior  and  draw  a  ray  to  it,  being  careful 
with  the  orientation  when  you  draw  it.  Traverse  along  the 
road  or  ray  and  keep  going  until  it  seems  advisable  to  stop. 
Then  plot  your  position,  fill  in  flat  detail  up  to  your  location, 
determine  your  elevation,  and  then,  after  orienting  the  board, 
draw  rays  to  such  stream  junctions  and  high  points  as  seem 
to  be  valuable.  In  this  manner  traverse  across  the  entire  area, 
locating  stream  lines,  stream  junctions,  ridges,  and  hilltops, 
fill  in  flat  detail,  determine  elevations  as  you  go  and  note  those 
of  critical  points  along  and  near  your  traverse.  It  may  be 
necessary  to  traverse  across  the  area  in  the  other  direction  be- 
fore all  critical  points  are  determined,  but  on  such  a  small 
area  it  will  probably  not  be:  After  having  located  the  drainage 
framework  and  ridge  lines  and  determined  their  elevations 
you  are  ready  to  contour.  This  should  be  done  by  noting  the 
slopes  as  uniform,  concave  or  convex,  and  spacing  the  contour 
lines  accordingly.  After  a  little  practice,  it  should  be  possible 
to  contour  any  area  that  the  sketcher  has  been  over,  from  one 
or  two  places  from  which  he  is  able  to  see  the  slopes.  Until  the 
sketcher  becomes  pretty  familiar  with  ground  forms  and  their 
representation  by  contours,  he  should  take  time  to  dot  in  the 
crossing  points  of  the  contour  lines  between  all  adjacent  critical 
points.  This  will  take  a  little  longer  but  will  save  much  time 
later  because  of  the  practice  it  gives  the  hand  and  eye. 

Put  on  the  title  as  described  on  page  26,  and  the  sketch  is 
finished. 

OUTPOST  SKETCH. 

In  the  execution  of  an  outpost  sketch,  which -is  made  on  a 
scale  of  6  inches  to  the  mile,  V.  I.,  10  feet,  the  methods  followed 
are  the  same  as  those  of  a  position  sketch,  except  that  the 
sketcher  is  confined  to  one  side  of  the  area. 

Points  along  the  outpost  line  are  located  by  traversing,  while 
those  to  the  front  are  determined  by  intersection  or,  in  some 


SKETCHING  METHODS.  47 

cases,  by  estimation,  as  for  instance,  where  a  feature  can  be 
seen  from  one  place  on  the  line  only. 

Having  made  two  or  three  position  sketches,  the  beginner 
should  be  able  to  start  at  one  end  of  the  line  and  carry  his  oper- 
ations along  to  the  other  end  and  then  from  some  advantageous 
position  contour  the  area. 

A  little  study  of  the  area  before  starting  the  sketch  will  be 
of  value  in  determining  the  best  method  to  follow. 

Traverse  the  outpost  line,  sketching  it  as  you  go,  and  draw- 
ing rays  from  different  stations  to  points  in  the  foreground, 
thus  locating  them  by  intersection. 

The  angle  between  the  intersection  lines  should  be  as  near 
90°  as  possible.  Therefore,  the  points  on  a  straight  line  from 
which  the  intersecting  lines  are  drawn  should  be  far  enough 
apart,  if  the  ground  will  permit,  to  secure  this.  It  is  thus 
evident  that  the  farther  out  the  points  are,  the  farther  apart 
should  be  the  points  from  which  the  intersecting  lines  are  drawn. 
Conversely,  the  nearer  the  object,  the  shorter  need  be  the  dis- 
tance between  the  points  on  the  traverse  line  from  which  the 
rays  are  drawn. 

The  distance  to  be  sketched  to  the  front  depends  upon  the 
time  available  and  the  character  of  the  country.  In  all  prac- 
tice work  the  sketcher  should  include  the  area  as  far  to  the 
front  as  he  can  see. 

It  is  frequently  the  case  in  outpost  sketching  that  it  is  pos- 
sible to  locate  and  draw  in  one  end  and  the  direction  line  of  a 
straight  road,  fence  line,  railroad  track,  or  telegraph  line.  If 
this  can  be  done,  all  points  along  it  are  accurately  located  by 
drawing  a  ray  to  them  from  determined  points  along  the  tra- 
verse, thereby  completing  the  intersection. 

In  contouring  the  outpost  sketch,  the  same  methods  are  fol- 
lowed as  in  the  position  sketch.  The  stream  line  and  ridge 
framework  have  been  secured  by  the  sketcher  in  his  traverse, 
and  it  only  remains  to  interpolate  the  contours  according  to 
the  slopes  of  the  ground  as  they  appear  to  the  sketcher. 

Any  part  of  the  area  that  can  not  be  seen,  as  the  far  side  of  a 
ridge  parallel  to  the  traverse,  is  drawn  in  by  broken  contour 
lines,  which  indicate  that,  in  the  opinion  of  the  sketcher,  the 
ground  is  shaped  as  shown  by  them,  although  he  has  not 
visited  it. 


4$  SKETCHING  METHODS. 

Field  glasses  may  be  of  use  in  outpost  sketching  in  picking  out 
objects  on  which  to  intersect  or  for  discovering  folds  in  the 
ground  that  are  not  visible  to  the  naked  eye. 

PLACE  SKETCH. 

A  place  sketch  is  one  in  which  the  sketcher  is  limited  to  a 
single  point  of  observation  overlooking  the  area  to  be  sketched. 
The  details  to  be  shown  are  the  same  as  on  a  position  or  outpost 
sketch. 

If  made  to  extend  a  road  or  position  sketch  farther  toward 
the  enemy  than  can  be  reached  by  the  sketcher,  the  place  sketch 
will  be  at  the  scale  of  the  sketch  thus  extended,  otherwise  at 
6  inches  to  the  mile  and  10-foot  V.  I. 

The  methods  of  work  described  for  making  a  position  and 
outpost  sketch  are  followed,  except  that  the  location  of  points 
is  determined  by  estimation,  assisted'  by  intersection  methods 
where  possible. 

It  is  advisable  to  select  some  few  prominent  features  in  the 
area,  determine  their  position  and  elevation  as  carefully  as 
possible,  and  then  use  them  as  reference  points  in  locating  other 
points.  A  road,  a  hedge  fence,  a  wire  fence,  a  railroad,  or 
any  such  feature  should  be  located  and  drawn  in  as  soon  as 
possible  and'  used  for  basing  other  estimates  and  for  locating 
points  along  it  by  intersection. 

Parts  of  the  area  that  can  not  be  seen,  but  which  the  sketcher 
is  able  to  estimate,  should  be  represented  by  broken  lines,  as  in 
outpost  work. 

Place  sketching  is  extremely  valuable  to  the  beginner,  who 
has  progressed  through  position  and  outpost  sketching,  on  ac- 
count of  the  practice  that  it  gives  in  estimating  distances. 

ROAD  SKETCH. 

Before  taking  up  road  sketching,  the  beginner  should  be  able 
to  make  a  position  sketch  and  should  have  made  a  few  outpost 
and  place  sketches,  for  the  benefit  of  the  practice  in  intersection 
and  estimation  which  he  gains  by  them.  He  should  also  learn 
something  of  what  can  be  shown  to  advantage  on  a  3-inch  scale. 

It  is  advisable  to  make  one  or  two  short  road  sketches  dis- 
mounted before  taking  up  the  road  sketching  proper,  which  is 
done  mounted. 

The  methods  followed  in  road  work  are  a  combination  of 
those  used  in  the  other  classes  of  sketches  which  have  been 


SKETCHING  METHODS.  49 

described.  The  scale  is  usually  3  inches  to  1  mile  with  V.  L, 
20  feet.  The  sketcher  lays  the  board  on  the  ground  or  places  it 
on  his  knees  as  he  sits  down. 

The  road  sketch  should  include  all  the  country  for  400  yards 
to  each  side  of  the  road,  all  artillery  positions  within  several 
miles,  and  all  commanding  positions  within  rifle  range  of  about 
1  mile.  It  should  show  any  prominent  landmarks  and  where 
roads,  railroads,  etc.,  come  from  and  go  to,  the  names  of  rivers 
and  larger  streams,  of  the  families  living  at  crossroads  or  in 
isolated  houses,  of  towns  or  villages,  as  well  as  all  information 
that  is  given  in  position,  outpost,  or  place  sketches. 

Arriving  at  his  second  station,  the  sketcher  should  draw  in 
not  only  all  horizontal  detail  from  the  first  station,  but  should 
contour  the  area  he  has  passed  over  before  starting  on  his  next 
traverse.  It  is  for  this  reason  that  it  is  considered  better  for 
the  beginner  not  to  attempt  to  make  a  road  sketch  until  he  is 
somewhat  practiced  in  sketching  methods. 

Do  not  waste  time  in  orienting,  but  after  laying  board  down 
or  standing  up  with  it  leveled  in  front  of  and  pressed  against 
the  body,  orient  by  back  sight  and  check  by  noting  that  arrow 
on  board  is  to  north. 

With  the  board  held  pressed  against  the  body,  to  draw  a 
ray  to  a  distant  object,  first  orient  the  board,  then  pivot  the 
ruler  around  the  pin  to  its  approximate  position,  and  glancing 
down  at  the  ruler  and  at  the  object  alternately,  deter  mine -when 
the  ruler  is  pointing  at  the  object.  Glance  at  the  orientation, 
carefully  secure  the  ruler  with  finger  or  thumb,  and  then  draw 
the  ray.  This  will  be  found  quite  difficult  to  do  at  first,  but  a 
little  practice  will  make  it  easy.  Points  determined  by  inter- 
section of  rays  taken  in  this  manner  are  very  accurately  located 
after  some  practice. 

The  road  sketch  is  carried  along  in  the  manner  indicated  from 
station  to  station,  being  completed  at  each  point  before  moving 
on  to  the  next. 

Many  points  within  400  yards  of  the  road  will  not  be  visible 
to  the  sketcher  from  his  position  opposite  them  in  the  road, 
but  they  may  be  from  some  point  further  on.  In  any  case,  make 
it  a  rule  not  to  leave  the  road.  Fill  in  such  places  as  you  think 
they  are,  as  described  in  outpost  work,  or  leave  them  blank, 
as  their  character  will  be  seen  by  the  reader  of  the  sketch. 


60  SKETCHING  METHODS. 

In  case  the  sketch  should  threaten  to  run  off  the  paper,  the 
procedure  is  to  fill  in  the  detail  a  little  beyond  your  station 
(which  is  now  close  to  the  edge  of  the  paper)  and  then,  choosing 
a  new  point  of  beginning  on  the  paper,  locate  your  station  there, 
draw  a  magnetic-meridian  line  near  by,  and  duplicate  the  filling 
in  previously  done,  around  and  beyond  it. 

Go  right  ahead  with  this  part  just  as  though  the  other  part 
was  a  different  sketch,  but  when  the  sketch  is  finished  cut  the 
paper  between  the  two  parts,  and  laying  the  points  which  you 
filled  in  twice  (once  near  the  edge  of  the  paper  and  again  when 
you  started  the  new  part),  one  over  the  other,  turn  the  papers 
until  the  M.  M.  lines  of  the  two  parts  are  parallel,  and  then 
paste  them  together  in  that  position.  The  sketch  may  run  off 
the  paper  several  times,  but  so  long  as  the  finished  sketch  shows 
the  meridian  lines  of  all  different  parts  parallel  to  each  other 
this  is  immaterial. 

In  mounted  work  the  sketcher  must,  while  controlling  the 
horse  and  riding  along  the  road,  jot  down  the  features  as  they 
are  passed.  This  is  done  on  the  pad  as  described  on  page  20. 

Practice  in  noting  down  features  while  riding  at  a  trot  should 
be  had  before  going  out  to  make  a  sketch.  It  is  quite  difficult 
for  some  to  learn,  but  anyone  can  do  it  with  practice. 

System  in  methods  of  work  is  most  important,  as  time  is  a 
big  factor  in  mounted  work.  All  sketching  is  done,  as  in  road 
sketching,  dismounted.  The  board  is  swung  under  the  left  arm 
by  the  cord  passing  over  the  shoulder,  and  the  watch  (if  using 
the  stop  watch)  and  pad  are  held  in  the  left  hand,  finger  close 
to  the  stop  of  the  watch.  Using  the  stop  watch  and  pad  is 
largely  for  convenience.  Satisfactory  mounted  work  may  be 
done  by  using  an  ordinary  wrist  watch  on  inner  side  of  left  wrist, 
from  which  the  time  of  passing  a  feature,  etc.,  may  be  noted  on 
a  pad  held  in  left  hand. 

The  reins  are  held  in  the  right  hand,  over  left  wrist,  or 
with  a  '  :not  tied  in  them  across  the  pommel  of  the  saddle,  where 
they  can  be  quickly  grasped. 

If  you  have  an  assistant,  which  is  desirable,  have  him  carry 
the  board  and  hold  your  horse  when  you  halt.  The  assistant 
should  be  with  you  while  rating  the  horse  and  ride  either 
abreast  of  or  behind  you,  as  he  is  to  do  during  the  sketching. 

Immediately  after  mounting  take  the  pad  in  left  hand.  As 
the  horse  starts  press  the  stop,  being  careful  to  see  that  stop 
watch  is  at  zero, 


SKETCHING  METHODS.  51 

> 
Keep  your  eyes  on  the  country  and  on  your  watch  alternately, 

so  that  when  you  see  a  feature  you  will  not  have  to  hunt  for  o 

the  proper  place  on  the  pad  to  locate  it.    It  may  be  necessary  § 

at  first  to  stand  in  your  stirrups  and  lean  forward  with  arms  ^ 

close  in  while  making  the  marks  in  order  to  get  readable  ones.  ££J 

Note  the  direction  of  flow  of  the  stream  lines  as  you  pass  them.  _L 

At  first  traverse  about  a  minute  at  a  time  and  then  dismount       ££ 

(Ji 
and  complete  the  sketch  in  the  same  manner  as  in  road  sketching 

dismounted.     The  time  spent  in  traversing  is  small  in  compari-      o> 
son  with  that  spent  in  plotting  the  notes  taken. 

Arriving  at  a  halting  place,  stop  the  horse,  press  the  watch 
stop  to  secure  correct  time  or  note  same  from  watch,  throw 
sketch-board  cord  over  the  head  and  lay  the  board  on  the 
ground,  or  sit  down  and  place  it  on  your  knees.  It  is  better  to 
lie  down  on  the  ground  on  the  stomach  and  with  pad  at  hand 
and  the  board  on  the  ground,  measure  off  the  minutes  of  travel 
and  fill  in  flat  detail  and  critical  points  according  to  the  notes. 
Then  orient  the  board  and  draw  a  ray  to  the  new  station  or  in 
the  new  direction  along  the  traverse.  Then,  taking  the  board 
up  as  previously  described,  contour  the  sketch  up  to  your 
position. 

In  field"  service  the  information  desired  in  a  road  sketch 
is  largely  that  which  will  enable  another  to  follow  tbe  recon- 
noitered  road.  For  this  reason  contouring  is  of  less  importance 
than  direction,  distance,  land  marks,  and  condition  and  practi- 
cability of  roads.  In  learning  how  to  sketch,  however,  it  is  con- 
sidered necessary  that  the  sketcher  practice  contouring  in  road 
sketching,  not  so  much  because  he  will  do  this  in  service  as 
because  the  practice  in  rapid  contouring  is  invaluable  in  the 
study  of  ground  forms  and  their  representation. 

RECONNAISSANCE  SKETCHES. 

The  tactical  situation  and  the  intentions  of  the  commander 
will  indicate  in  each  case  the  information  that  is  especially 
desired.  The  information  secured  is  conveyed  by  means  of  a 
sketch  amplified  by  a  report  in  marginal  notes  numbered  se- 
rially. All  information  that  it  is  possible  to  show  clearly  is 
contained  in  the  sketch.  The  report  consists  of  descriptions  of 
features  and  objects,  measurements,  material,  construction,  etc., 
which  can  not  be  conveyed  in  a  sketch.  The  serial  reference 
numbers  should  run  in  order  on  tlie  fflargin,  The  numbers  are 


52  SKETCHING  METHODS. 

placed  on  the  sketch  near  the  object  to  which  they  pertain,  so 
that  it  will  be  clear  to  what  they  refer.  In  making  the  notes 
clearness  and  brevity  are  desirable.  Such  terms  as  "  before," 
"  behind,"  "  this  side  of,"  etc.,  should  be  avoided  and  compass 
directions  used.  The  terms  "  16ft  "  and  "  right "  may  be  used  in 
referring  to  the  banks  of  a  stream,  in  which  case  the  sketcher 
is  assumed  to  be  facing  downstream. 

o 


